Sonic Runners

Sonic Runners (ソニックランナーズ) was a side-scrolling platform video game in the Sonic the Hedgehog series, developed by Sonic Team for the Android and iOS mobile platforms. It was first announced by publisher Sega on 28 December 2014. It later came out in Japan and Canada on 25 February 2015 before coming out worldwide on 25 June 2015. As of 7 December 2015, Sonic Runners has received over six million downloads worldwide, with more than five million downloads from Google Play. On 27 July 2016, Sega closed the game's servers and pulled the game out of its respective store apps. The game later had a sequel named Sonic Runners Adventure.

Development
Development for Sonic Runners began in 2013 according to Takashi Iizuka. However, In February 2014, a poster hosted at a German toy fair announced a 2015 Sonic game for the PlayStation 4, Xbox One and Wii U, as well as the Sonic Boom games, a feature film, and Mario & Sonic at the Sochi 2014 Olympic Winter Games. This information circulated on the Internet, especially concerning the unannounced Sonic game, but Sega quickly asserted that the information on the supposed new title was false. Later in 2014, however, rumors of a smartphone game titled Sonic Runners began to circulate online; Sega had registered the domain name sonicrunners.com in July of that year. On 28 December 2014, Sonic Runners was eventually announced by Sega during the annual “Sonic Fan Thanksgiving” event at one of their Joypolis amusement parks. At the event, Takashi Iizuka personally revealed that Sonic Team’s next project was “Sonic Runners“ on the mobile. He promised that more information about the game would be revealed sequentially, starting in January 2015, but nothing was released during that month. Its gameplay style was quickly speculated by fan to be an endless runner, like Sonic Dash, which is also a smartphone game.

A small teaser and more details about the game were revealed on 3 February 2015. According to Takashi Iizuka, the game will be a "2D side-scrolling runner with stages that can be played in a minute or two." On 3 February 2015, Tomoya Ohtani announced on Twitter that he would be composing the musical score for the game.

Plot
The story follows Sonic, Tails, and Knuckles as they follow Dr. Eggman through different areas as he hatches various plans in succession, with the core goal of retrying his mind control cannon from Sonic Colors. Team Sonic usually runs into these situations unintentionally, finding Animals or Wisps in trouble, Orbot or Cubot carrying out orders, or robots walking around where they should not be. Along the way, the team have several side-adventures where they help Animals, Wisps and Chao with issues or just travel new places. Another subplot involves Team Sonic going on the hunt for Master Emerald fragments after Knuckles was forced to shatter the Master Emerald to stop Eggman from stealing it.

The last story arc revolves around Dr. Eggman who has stolen the Chaos Emeralds and drained them of their power to provide the last fuel needed for his mind control cannon. Team Sonic thus set out to reclaim the drained Emeralds before facing Eggman in a final showdown. Amidst this, Sonic reabsorbs the Chaos Emeralds' energy back into the Emeralds as Eggman uses his mind control cannon on him and becomes Super Sonic. Using his newfound power, Sonic destroys the mind control cannon and peace reigns over the world once more, though Eggman still gave the heroes the slip.

Windy Hill in Spring Event
At Omochao's wish, Team Sonic enter a Easter competition prepared by the Animals and Chao. While hunting for Easter eggs, they come across Orbot and Cubot laying traps between the eggs. As the heroes confront Eggman's lackeys, however, Metal Sonic appears and saves the duo, but not before Cubot reveals their boss' whereabouts. At the foretold factory, Sonic, Tails and Knuckles find animals being forced to build fake Easter Eggs for Eggman and save them after fending off Metal Sonic together, heading to the factory's base afterwards. As they confront Eggman, the unprepared Doctor commands Orbot and Cubot to eliminate the intruders, but when both are unable and unwilling to, Eggman is easily defeated by the trio, who then decide to continue with the tournament.

Puyopuyo!! Quest Collaboration Event
Team Sonic find raining down on earth and run into  and Accord who have no clue to how they got there. With the world being filled with Puyo Puyos, Sonic accepts Accord's request to find their other friends to stop the crisis. Along the way, it is revealed that Dr. Eggman has used the magic of a Puyo Coin to join the two worlds together so he could harness the power of magic users for a new weapon. As Team Sonic proceeds with their search, Eggman gets in over his head with the magic users and is forced to escape when his prisoner retaliates. Thanking Team Sonic for their help, the Puyo Puyo return home with all the objects from their world.

Happy Birthday Sonic!
As Sonic, Tails and Knuckles head to Sonic's birthday party, they find the party trashed and their friends kidnapped by Dr. Eggman. To make matters worse, Eggman has begun a new scheme for world domination, having created Death Egg drones as his military force. Thanks to teamwork and help from their allies, Team Sonic rescued their friends and foiled Eggman's plans. They then returned to the party to celebrate Sonic's birthday.

Desert Ruins Event
Team Sonic discovers a fragment of the world of the Arabian Nights above their world and decide to go there to hunt treasures. Along the way, they discover that the Erazor Djinn has been freed, but got split into a thousand weaker pieces which Eggman, who has taken King Shahryar's place, is gathering one hundred of to form a super-djinn to take over the world with. Using Eggman's own strategy against him however, Team Sonic stopped Eggman and restored Shahryar to the throne.

Tropical Coast Event
Team Sonic are on vacation at a beach resort when they find Eggman stealing the beach's many pearls to finance his bases. As they head out to stop Eggman, Team Sonic meet some Wisps and learn that Eggman has kidnapped Mother Wisp while she was visiting her children. With Team Rose's aid, Team Sonic track down Eggman, but are too late to stop Eggman from turning Mother Wisp into Dark Mother Wisp. When Dark Mother Wisp proves too powerful for Eggman to control though, she goes on a rampage until her Wisp children calms her down, reverting her back to normal. Team Sonic and Team Rose thus focus on getting back every pearl Eggman stole.

Zazz Raid Event
While on their own, Team Sonic learns from some White Wisps that Zazz has returned and has been stealing Power Rings, a special type of Rings that makes their wielder extremely powerful. The heroes track down Zazz and learn that he is accumulation Power Rings so he can get revenge at Sonic after he lost in their last encounter. Despite the Zeti's new power though, Team Sonic continuously defeats Zazz. Between his battles, Zazz talks with the Deadly Six, who confront Zazz about his attempts to either advise him, tease him or further their own agendas.

Halloween Event
Coming to a Halloween party, Team Sonic are attacked by the dressed-up Animals. Deciding to investigate, the discover that the Animals have been brainwashed by candy from Dr. Eggman which Orbot and Cubot have been handing out. Tracking the brainwashed Animals, Team Sonic find Rouge who has been investigating this herself with E-123 Omega. Needing someone to check a lakeside castle, Rouge gives Team Sonic a Boo to guide them.

At the castle where Team Sonic meet brainwashed Boos, they find Eggman as he releases King Boom Boo and brainwashes him into serving him. It is then revealed that Eggman is using the Animals to built a Halloween theme park and has King Boom Boo guard it. Unable to defeat King Boom Boo, Team Sonic gets Rouge and Omega who have discovered Eggman's candy wears off in strong light. Using Omega's searchlights, the heroes free the Animals and King Boom Boo, with the latter starting to chase Eggman in vengeance. The heroes then decide to return to the Halloween party.

Gameplay
Sonic Runners is a 2D side-scrolling runner with stages that can be played in a minute or two. The player can tap to perform jumps and move the characters. Using Chao, Buddies, items and radio controlled toys, the player's objective is to get the highest score for a level. By doing so, the player can also collect Crystals, which increase the score as long as the player is keeping the combo going.

At the end of a majority of chapters (Unless the plot doesn't involve him like "Ring Hill", or they simply don't run into him, which usually hails an item of some kind instead), the player also has to engage in boss battles with Dr. Eggman, who has variations on his Egg Mobile. These variations have differing weapons, but commonly involve dodging weapons centered around Spiked balls and jumping into the Yellow Ball contained in others, which will fly back into his machine and damage him.

Progressing the game's episode as Sonic will eventually unlock more playable Sonic series characters, such as Miles "Tails" Prower and Knuckles the Echidna. Additionally, the game was updated to include more characters as well. Each character has their own different action and their levels can be raised using Rings collected in the stages. When collecting Rings in stages, the player can bank them when passing Star Posts.

The characters are best used in "Specialist Areas". While the levels are playable as any character, specific character types are more suited to these levels, with more accessible areas using their abilities. The regions themselves carry specific aesthetics (Windy Hill = Speed, Sky Road = Flight, Lava Mountain = Power, etc.). An emblem next to the chapter title on the menu screen notes which type is recommended.

Playable characters
Each character has an Ability Type (Speed, Fly, Power) and a Personality Type and can be leveled up to Level 100 by spending or earning Rings from playing. Leveling up characters increases the duration of Equippable Items, enhances Distance Bonus, Ring Bonus and Animal Bonus up to 20% per character. Easy Type characters cost less Rings to level up than other characters. By reobtaining characters, their "Limit Break" levels up to Level 10, giving them additional time for Timed Mode by five seconds each level and increasing their Score Bonus by 10% each level.

Non-playable characters

 * Dr. Eggman
 * Orbot
 * Cubot
 * Animal friends
 * Flicky
 * Pocky
 * Pecky
 * Cucky
 * Ricky
 * Picky
 * Rocky
 * Chao
 * Hero Chao
 * Dark Chao
 * Omochao
 * Wisps
 * White Wisp
 * Cyan Wisp
 * Yellow Wisp
 * Indigo Wisp
 * Erazor Djinn
 * King Shahryar
 * Yacker
 * Chip
 * Deadly Six
 * Zazz
 * Zomom
 * Zik
 * Zeena
 * Zor
 * Zavok

Regular Stages
The game has three main zones, all of which are from Sonic Lost World. Each stage has its own Type to show which character Type is best suited to use on the stage. Before reaching Episode 40, every Episode has a fixed stage, but afterwards, the stages will be randomly chosen, a small icon at the bottom right end of the screen showing which stage will appear next.

Special Stages
For various in-game events, Sonic Runners offers Special stages only available for a limited time. Throughout these stages, certain collectibles are scattered, which have to be collected in order to proceed in the event's story, unlock rewards and climb up the event leaderboards. The event stages are not suited for a specific character Type as the layout and obstacles constantly change between those of Windy Hill, Sky Road and Lava Mountain, meaning every character can be used without having a disadvantage. While featuring all enemies from Regular Stages, Desert Ruins also has Boo as an enemy.

As of v.2.0.0, Special Stages are now taking place on Timed Mode, removing any Story content, event leaderboards and rewards that were available in earlier versions of the game, with the competition instead taking place on the regular Timed Mode leaderboards.

Boss Battles
There are currently three different types of bosses in Sonic Runners, each of them being controlled by Dr. Eggman. A Showdown is usually awaiting at the end of each Episode, though there are also a few Episodes without one at the end. The boss must be defeated in order to progress to the next Episode, and the player can also gain a Special Egg by completing the Showdown on the first try. Whereas Eggman only needs three hits to defeat in the first Episode, his Health Points increase up to 20 until Episode 50. Boss Battles also get faster and more difficult as the player progresses through the Episodes. Showdowns always take place in one of the regular stages of the game, though the setting does not influence the nature of the Boss Battle.

Buddies
Buddies, formerly called "Companions", are companions which the player's characters can take along during a level. Some help raise the player's score while others can enhance item effects. Just like the playable characters, the Buddies have a certain attribute, meaning that their effects will be amplified when paired up with the "right" player character. At first there was only twenty different types of them, but more have been added over time. Like the playable character, the Buddies can be leveled up to Level 10.

Normal Buddies
Normal Buddies are only available on the BIG and SUPER roulette wheel within the Item Roulette.

Rare Buddies
Rare Buddies are available in the Premium Roulette and the Special Roulette, unlocked when the spinner lands on a segment with a grey, Rare Egg.

S Rare Buddies
S Rare Buddies are available in the Premium Roulette and the Special Roulette, unlocked when the spinner lands on a segment with a golden, Super-Rare Egg.

Collectible Items

 * Rings: Can be collected regularly in-game from long strings, large groups the middle-air or equipped from Item Boxes. Taking damage once without Shield or being Invincible will make the player lose all Rings. Each Ring grants a single point to the score. Completing an episode will also reward the player with Rings.
 * Red Star Rings: these are used as currency when the player loses a life. The player has to pay five Red Star Rings if they want to continue. They can be from equipped from the shop, but they can also pop out randomly from Eggman's Egg Mobile during boss battles. Completing an episode also rewards the player with Red Star Rings. Red Star Rings can also be used to spin the Premium Roulette to get Buddies or Characters.

Equippable Items
Items help players achieve better performance. Up to three Items can be equipped, but all of them can be occasionally found during a run. However, equipped items last about twice as long as items found in a stage. Every item is available for free once a day.

Booster Items
Other than equippable items, Booster Items do not have a timer and affect the whole run. They can be bought using Rings, but each of them is available for free once a day.

List of Episodes

 * Episode 1-1: It's Doctor Eggman, the evil scientist! The evil genius Dr. Eggman is back to sow chaos in Sonic and the Animals' peaceful world.
 * Episode 2-1: Save the Animals! Sonic and friends drove Dr. Eggman away, but he won't give up, and is kidnapping Animals again!
 * Episode 3-1: Dr. Eggman's Dirty Tricks Sonic and friends foiled Eggman's plan to turn Animals into robots, but just what WAS he planning?
 * Episode 4-1: Little Chao Lost Sonic and friends come across a lost chao, and decide to help it get home safely!
 * Episode 5-1: A Not-So-Heavy-Load Dr. Eggman had ordered Cubot to collect items [to get] ready for his big comeback. But can Cubot deliver...?
 * Episode 6-1: Evening Patrol Sonic and friends hear some Animals calling out in fright. Better find out what's up...
 * Episode 6-2: Evening Patrol 2 Sonic and friends are on their way to fetch a translation unit so they can talk to the White Wisp.
 * Episode 7-1: Earthquake Island Pinky says there have been a lot of earthquakes lately, and asks Sonic and friends to investigate...
 * Episode 8-1: The Mysterious Light Ricky and his friend get a fright from a mysterious light on the way home. Find out the truth behind it!
 * Episode 9-1: Disaster Zone The Friends find the remains of a great disaster, and are asked by the local Animals for help...
 * Episode 10-1: Dr. Eggman's Robot Army Attacks! Eggman's robot army attacked an Animal village! Invade Dr. Eggman's base and save the Animals!
 * Episode 11-1: Chasing our Tails Having managed to drive Dr.Eggman away, the gang follow Tails as he guides them to an all-new area!
 * Episode 11-2: Chasing our Tails 2 Tails leads the way as the gang investigate an all-new area - home to one of Dr.Eggman's bases!
 * Episode 12-1: Picky's Pig-Out Sonic and co. bump into Picky, and the poor pig's real hungry! They'd better find him some food!
 * Episode 13-1: Little Pocky Lost Pocky's crying because he's lost his mother. It's up to Sonic and co. to reunite them!
 * Episode 14-1: Ricky's Request Dr.Eggman has built a factory right next to Ricky's home, and it's polluting the water! Do something!
 * Episode 15-1: Ring Hill Knuckles remembers a rumor about a place called Ring Hill, and the gang decide to go check it out!
 * Episode 16-1: Dr. Eggman's Secret Experiment Sonic and friends hear a rumor that Dr.Eggman is conducting a secret experiment. Time to investigate!
 * Episode 16-2: Dr. Eggman's Secret Experiment 2 Sonic and friends have found Dr.Eggman's base. Now it's time to find out what he's up to!
 * Episode 17-1: Goodbye Greenery Pocky needs help! All the greenery is disappearing from the hills where he lives!
 * Episode 18-1: Damsel in Distress Rocky's girlfriend has gone missing. Help him to find her!
 * Episode 19-1: The Animals Fight Back The gang visit the Animals' village, but there are no Animals to be found! Where have they all gone?!
 * Episode 19-2: The Animals Fight Back 2 Sonic and co. have agreed to help the Animals with their plan - but just what ARE they planning?
 * Episode 20-1: Sonic the Villain The animals are suddenly scared of Sonic, and won't come near him... What on earth is going on?
 * Episode 20-2: Sonic the Villain 2 Metal Sonic has been pretending to be the real Sonic and scaring the Animals. After him!
 * Episode 21-1: Flicky Gets Flustered Flicky can't find his little brother, and comes to ask Sonic for help. Can the gang help him out?
 * Episode 22-1: Wisps from On High Mysterious creatures are getting the Animals agitated. The gang think they're Wisps, and go looking for proof!
 * Episode 22-2: Wisps from On High 2 Eggman is taking the Wisps back to his base! Can Sonic catch up with him and free the colorful creatures?
 * Episode 23-1: Showdown with Eggman's Airforce Dr. Eggman's airforce are preventing Flicky from taking to the skies! Find Dr. Eggman's airbase!
 * Episode 23-2: Showdown with Eggman's Airforce 2 Eggman left Orbot in charge, so Sonic had no trouble disabling the base. Now to find the man himself!
 * Episode 24-1: Angel Schmangel Cucky and Omochao say they've seen an angel. Time for Sonic and friends to find out what's really going on...
 * Episode 24-2: Angel Schmangel 2 The "angel" turned out to be a Hero Chao, and now Metal Sonic has kidnapped it! Sonic to the rescue!
 * Episode 25-1: Treasure in the Clouds The Hero Chao tells the gang about a treasure hidden in the clouds, and Knuckles is keen to seek it out!
 * Episode 26-1: Birdly Paradise Dr. Eggman's forces have taken over Cucky's place! Drive them away so Cucky can get his life back!
 * Episode 27-1: Little Walrus Lost Sonic and co. find Rocky in a panic, and unable to find his way home. It's up to them to help him!
 * Episode 28-1: Penguins Might Fly Pecky and his pals used to fly freely round these parts - until Eggman showed up. Now they're grounded!
 * Episode 29-1: Guarding the Sky Temple Some Animals come to Sonic and co. asking for help, and offer to guide them to Dr. Eggman's latest base...
 * Episode 29-2: Guarding the Sky Temple 2 The "Animals" were really Orbot and Cubot! Time to interrogate them and find out what Eggman's up to...
 * Episode 30-1: Bring on the Dawn! The sun has stopped rising in Cucky's part of the forest, so there's nothing to crow at! Do something!
 * Episode 31-1: After that Emerald! Flicky comes to speak to Knuckles, and he's all aflutter - Eggman's after the Master Emerald!
 * Episode 31-2: After that Emerald 2 The Master Emerald has been stolen! Sonic and co. need to find Dr. Eggman and get it back!
 * Episode 32-1: A Red-Hot Winter Pecky's village has suddenly become unbearably hot. It's up to Sonic and co. to find out what's going on!
 * Episode 33-1: The Hunt for the Master Emerald After shutting down Dr. Eggman's factory, the gang find Pocky waiting with some important information!
 * Episode 33-2: The Hunt for the Master Emerald 2 Metal Sonic has run off with a fragment of the Master Emerald. Sonic and friends set off in hot pursuit!
 * Episode 34-1: Ricky's Request Ricky's found a tree that he can't cut down, no matter how hard he tries! Time for Sonic to give it a try!
 * Episode 35-1: The Dragon's Hoard The map Sonic and pals found is actually a treasure map! Time for a spot of treasure-hunting!
 * Episode 36-1: The Hunt for the Master Emerald 3 Now that they have an Emerald Detector, it's time for the friends to get back on the trail of the fragments!
 * Episode 36-2: The Hunt for the Master Emerald 4 Sonic and pals have headed up to the clouds in search of a Master Emerald fragment.
 * Episode 37-1: A Gift for Mama The gang's Master Emerald sensor leads them to Picky. Can he be persuaded to part with his fragment?
 * Episode 38-1: The Hunt for the Master Emerald 5 Dr. Eggman has taken Picky - and the Master Emerald fragment too! Get after him!
 * Episode 38-2: The Hunt for the Master Emerald 6 Dr. Eggman has run off with the Master Emerald fragment! Time to chase him down!
 * Episode 39-1: Guardians of the Master Emerald Having assembled all the Master Emerald fragments, the gang head to the temple to put it back together...
 * Episode 39-2: Guardians of the Master Emerald 2 Just as Sonic and pals are thinking of how to protect the Master Emerald, Omochao appears!
 * Episode 40-1: The Eggman's Plans The Animals are convinced that Dr. Eggman's up to his old tricks. Time to find out what he's planning...
 * Episode 40-2: The Eggman's Plans 2 It seems Flicky might have some information about Dr. Eggman...but might also be in need of rescuing!
 * Episode 40-3: The Eggman's Plans 3 Flicky's been abducted by Eggman! Sonic and friends to the rescue!
 * Episode 41-1: Uncovering Eggman's Plans Sonic and pals learn that Dr. Eggman has been collecting Chaos Emeralds. The question is: Why?
 * Episode 41-2: Uncovering Eggman's Plans 2 Dr. Eggman is trying to make a brainwashing laser to control the world! The gang have to stop it being fired!
 * Episode 41-3: Uncovering Eggman's Plans 3 Sonic and co. manage to get their hands on a Chaos Emerald detector. Now they just need to fix it...
 * Episode 42-1: Collecting the Chaos Emeralds Tails has fixed the detector, so it's time to go hunt down the Chaos Emeralds!
 * Episode 42-2: Collecting the Chaos Emeralds 2 Sonic and co. have followed the detector to one of Dr. Eggman's energy collection devices...
 * Episode 43-1: Collecting the Chaos Emeralds 3 Sonic and pals have found one Chaos Emerald, now it's time to round up the rest!
 * Episode 43-2: Collecting the Chaos Emeralds 4 Sonic and pals head for another one of Dr. Eggman's energy collection devices - this time with Cubot in tow!
 * Episode 44-1: Collecting the Chaos Emeralds 5 Sonic and co. have recovered the second Chaos Emerald. Now it's time to find the third!
 * Episode 44-2: Collecting the Chaos Emeralds 6 Having successfully evaded Orbot's traps Sonic and co. head for the third Chaos Emerald!
 * Episode 45-1: The Wisp Garden While looking for the fourth Chaos Emerald, the gang bump into a giant group of Wisps!
 * Episode 46-1: Collecting the Chaos Emeralds 7 Sonic and co. set out in search of more Chaos Emeralds - this time with Wisps in tow!
 * Episode 46-2: Collecting the Chaos Emeralds 8 Metal Sonic appeared out of nowhere and stole on of the Chaos Emeralds! Get it back!
 * Episode 47-1: Collecting the Chaos Emeralds 9 A powered-up Metal Sonic has swiped the gang's Chaos Emeralds! How are they going to get them back?!
 * Episode 47-2: Collecting the Chaos Emeralds 10 Having overcome Cubot without laying a finger on him, the gang head to the next energy collection device!
 * Episode 48-1: Collecting the Chaos Emeralds 11 Sonic and friends have avoided Metal Sonic and retrieved another Chaos Emerald. Onto the next one!
 * Episode 48-2: Collecting the Chaos Emeralds 12 Sonic and pals have survived Orbot's traps. Time to get the search for the Chaos Emeralds back on track!
 * Episode 49-1: Collecting the Chaos Emeralds 13 The gang have secured all the easy Chaos Emeralds - now it's time to take some risks!
 * Episode 49-2: Collecting the Chaos Emeralds 14 En route to find Chaos Emeralds, the gang prepare for a showdown with Metal Sonic...
 * Episode 50-1: Boiling Point With the brainwashing laser ready to fire, the gang get ready for the final showdown with Dr. Eggman!
 * Episode 50-2: Boiling Point 2 Sonic and co. have begun their invasion of Eggman's HQ. Next on the menu: More robots!
 * Episode 50-3: Boiling Point 3 Sonic and pals are making short work of Dr. Eggman's defenses. Next up: Orbot!
 * Episode 50-4: Boiling Point 4 Cubot's tip-off got the team safely through Orbot's traps. Time to go even deeper into Eggman's HQ!
 * Episode 50-5: Boiling Point: Finale Having managed to make their way past Metal Sonic, the gang are finally at the heart of Eggman's HQ...

Events
Several Events have launched for Sonic Runners, each time announced and advertised by in-game notifications as well as on the game's official twitter account.

Facebook Campaign
One of the unlimited Events, offering the player 10 Red Star Rings for each friend that signs up for Sonic Runners after sending him an invitation via Facebook. Additionally, Amy Rose will be unlocked if ten Facebook friends start playing the game. Following the update to v2.0.0, the unlockable character was changed to Gothic Amy.

The Chaotix Detective Agency Premium Roulette
An Event which started on March 5, 2015 and added Vector, Espio and Charmy as playable characters for the first time. By hitting the Character Egg on the Premium Roulette or the Special Roulette, players were able to unlock one of these three. It was possible to unlock the same character more than once, which would be compensated with 50 Red Star Rings, 3 Special Eggs and 10000 Rings. The campaign was at first scheduled to end on March 15, 2015, but was later extended due to popular demand, eventually ending on March 22, 2015.

Animal Rescue Event
A recurring Event which ran for the first time from March 13 to March 15, 2015. In this event, players are able to gain several rewards by collecting a certain amount of Animals in the stages, among them the RC Monkey, a Normal Buddy first introduced in the game during this event. From September 18 to September 21, the Animal Rescue Event returned wih the opportunity to unlock Normal Buddies other than the RC Monkey, those being Normal Chao, Omochao, Jewel Chao, Dark Chao, Gold Chao and Hero Chao.

Phantasy Star Online 2 Collaboration
Running from April 14 to April 19, 2015, players were able to win new Buddies in the Premium Roulette, all three of them from the world of Phantasy Star Online 2: The Normal Buddy MAG, the Rare Buddy Rappy and the Super Rare Buddy Kuna.

Windy Hill in Spring Event
The Easter Event for Sonic Runners, introducing the first Special Stage in the game called "Windy Hill in Spring", available from March 30, 2015 to April 6, 2015. By collecting Easter Eggs in this stage, players are able to climb up the rankings, unlock several prizes and proceed in new Story Events along the way. The Event also introduced three new buddies: Merlina, Easter Bunny and Easter Chao. While the former can be unlocked and leveled up by proceeding in the Event, the latter two are only available through the Premium Roulette.

The Easter Event returned on March 19, 2016 to March 28, 2016 where players were able to compete in the stage in Timed Mode and boost their score by collecting Easter Eggs.

Puyopuyo!! Quest Collaboration Event
An Event that started on June 10, 2015 and featured a crossover with the Puyo Puyo series. This Event introduced a Puyopuyo!! Quest themed Special Stage. Here, the player can collect Puyo Coins to climb up the rankings, unlock prizes, obtain rewards and much more. The Event also introduces Amy Rose dressed up as Amitie, dubbed "Amitie-Style Amy", as a new playable character and as well the trio of Purple Papurisu, Suketoudara and Carbuncle as new buddies. The player can get Amitie-Style Amy, Purple Papurisu and Suketoudara on the Premium Roulette and Carbuncle by collecting enough Puyo Coins. The Event ended on June 17, 2015.

From February 15 until February 22, 2016, Amitie-Style Amy and the event-specific Buddies returned to the Premium Roulette, except for Purple Papurisu which was handed out as a Daily Reward.

Happy Birthday Sonic!
The 24th anniversary Event for Sonic the Hedgehog which began on June 24, 2015. This Event offered Classic Sonic as a playable character, a new Special Stage, and three exclusive buddies: The Sega Genesis, The Death Egg and Cartridge. In this Special Stage some of the collectables are replaced with Birthday Cakes which the player can collect to get rewards like Items, Wisps, Red Star Rings etc. The Special Stage was available until July 7, 2015, while Classic Sonic was available to July 10, 2015.

Desert Ruins Event
An Event that started on July 16, 2015. This Event introduced the Desert Ruins as a Special Stage. Here, the player can collect treasure to climb up the rankings, unlock prizes and more. The Event also introduces three new buddies: the Erazor Djinn, Magic Lamp and Desert Chao. Erazor Djinn can be obtained by collecting treasure while the remainder can be obtained on the Premium Roulette.

The Desert Ruins Event returned on April 16, 2016 to April 25, 2016 where players were able to compete in the stage in Timed Mode and boost their score by collecting treasure.

NiGHTS into Sonic Runners...
From July 30 to August 13, 2015, Sonic Runners offered three Buddies from the "NiGHTS into Dreams..." series, those being NiGHTS, Reala and a Nightopian. All three of them were available in the Premium Roulette during this period.

Tropical Coast Event
An Event available from August 20 to August 27, 2015, which introduced the Special Stage "Tropical Coast in Summer", where players have to collect pearls in order to climb the Event Rankings, proceed in the new Episode and unlock various prizes such as the Super Rare Buddy Mother Wisp. The Event also added two new Buddies to the Premium Roulette, those being the Rare Buddies Blowfish Transporter and Marine Chao.

The Tropical Coast Event returned on May 14 to May 23, 2016 where players were able to compete in the stage in Timed Mode and boost their score by collecting pearls.

Sonic Adventure Event
At September 4, 2015, Chaos 0, the RC Tornado 2, and the Orca from Sonic Adventure were released as Buddies, and Tikal was released as a playable character, all of which could be earned on the Premium Roulette. Tikal exited the Roulette on September 25. While the three Buddies stayed on the Premium Roulette afterwards, their drop rates were lowered simultaneously.

The Sonic Adventure event returned on March 9, 2016 to March 14, 2016 in the form of an instrumental version of "Open Your Heart" replacing the BGM for both Story Mode and Timed Mode stages.

Zazz Raid Event
From October 6 to October 13, 2015, players were able to fight Zazz of the Deadly Six as a Raid Boss. By playing through regular stages, Zazz could be encountered and defeated to earn prizes as well as Power Rings which could be spent on the event-exclusive Boss Roulette, featuring Gold Rings and the RC Moon Mech Buddy as prizes. Additionally, the Buddies Star-Shaped Missile and RC Satellite were released on the Premium Roulette to support players during the boss battle. Growing stronger each encounter, players were also able to ask other players for help if they were unable to defeat Zazz in the given time limit.

Halloween Event
A Halloween-themed Special Stage event available from October 23 until November 1, 2015, featuring a spooky Stage called "Halloween". By collecting candy, players were able to climb the event's leaderboard, progress in the story and unlock various prizes such as the King Boom Boo Buddy. To multiply the number of candy collected, the Buddies Boo and Halloween Chao were introduced in the Premium Roulette.

Fantasy Zone Collaboration Event
The fourth Collaboration Event in Sonic Runners, featuring characters from the game Fantasy Zone. Exclusively available for the period of November 17 - December 8, 2015, the three Buddies Opa-Opa, O-Papa and Heavy Bomb were added on the Premium Roulette. While initially scheduled to end on December 1, the event was extended due to an unexpected emergency maintenance following the update to v2.0.0.

Christmas NiGHTS Collaboration Event
From December 18 to December 28, 2015, three new Buddies themed around "Christmas NiGHTS into Dreams..." were available on the Premium Roulette: Christmas NiGHTS, Christmas Nightopian and Ideya.

Christmas Event
To celebrate Christmas, a new Special Stage became available in Timed Mode exclusively from December 19 until December 28, 2015, where presents could be collected in order to climb the Timed Mode leaderboards. Additionally, Christmas Sonic, Christmas Tails and Christmas Knuckles were available on the Premium Roulette during this period. Simultaneously, a Christmas Yeti, an ordinary Yeti and Arctic Chao were released as Buddies on the Premium Roulette.

Frozen Factory Event
The first Special Stage event in 2016, featuring Frozen Factory from Sonic Lost World. From February 20 until February 29, 2016, players were able to compete in the stage in Timed Mode and boost their score by collecting Snowflakes.

Release
Sonic Runners received a sudden soft-launch on 25 February 2015 and in the Japanese and Canadian App Store and Play Store app marketplaces. A few months later, in 25 June 2015, it was made available worldwide. It is available for free on recent iOS and Android devices, and contains in-app purchases.

Closure
On May 27, 2016, Sega announced that the game's service will be closed down on 27 July 2016. Red Star Ring sales ended on 27 May 2016 and any purchasing prior to that date will not be usable or redeemable after the closure of service.

Reception
Upon the game's announcement, Thomas Whitehead of NintendoLife voiced disappointment at Sonic Runners not being a Wii U title. Similarly, Tatiana Morris from GameZone hoped that it would not be the only Sonic game of the year, instead wishing for a console game similar to Sonic the Hedgehog or Sonic Adventure. Destructoid staff writer Brett Makedonski opined that while "it's tough to imagine Sonic fans getting too excited about Sonic Runners", its future augured well after the critical panning of Sonic Boom: Rise of Lyric and Sonic Boom: Shattered Crystal.

Upon release, Sonic Runners on iOS platforms has received mixed reviews. Destructoid gave Sonic Runners a 6/10, stating that the gameplay was fun, and that the developers should "take pride in their work", but criticized it's heavy emphasis on "pay to play". "The Jimquisition" called the gameplay "solid, but panned the game for it's many ads, the pay to win emphasis, and terrible load times, assigning the title a 4.5/10. Echoing these thoughts was Shaun Musgrave of Touch Arcade, who praised the core gameplay, but criticized the game for it's overabundance of monetizing, in the end giving it a low score of a 2/5. However, later reviews lightened up on the game, though the general consensus was generally the same; the core gameplay was fun, but the monetization and load times hampered the experience to mediocrity. It currently holds a Metacritic critic average of 51/100 ("mixed or average reviews"), with fan averages showing a current average of 6.9/10. GameRankings was slightly more positive, holding a 58.75%, though this is probably due to it's stricter requirements.

In contrast, Google Play's average for the Android version is rather positive, garnering a 4.0/5 from over 70,000 user ratings. With 30 million yen per month, Sega considered Sonic Runners a "failure" in its market.

Trivia

 * This game features the most playable characters ever in the Sonic the Hedgehog series.
 * Not counting their co-production credits in Sonic the Hedgehog 4, this game marks the first time Sonic Team themselves have ever developed a mobile game.
 * In terms of playability, Sonic Runners marks the return of many characters that were not used for a long time.
 * Big's last playable role was in Sonic & Sega All-Stars Racing, a game released in 2010.
 * Omega's last playable role was in Sonic Chronicles: The Dark Brotherhood, a game released in 2008.
 * The Werehog's last playable role was in Sonic Unleashed, a game released in 2008.
 * Charmy's last playable role was in Sonic Heroes, a game released in 2003.
 * Tikal's last playable role was in Sonic Adventure 2: Battle, a game released in 2001.
 * Mephiles, however, was a boss character in Sonic the Hedgehog, a game released in 2006. This makes him the only character in the series never to have been playable prior to this game.
 * This is the first game to feature Charmy with a running animation rather than just a flying animation.
 * When performing a dash, Sonic, Tails, Knuckles, Shadow, Blaze, Charmy, Classic Sonic and Werehog curl into a ball, Amy, Big, Espio, Vector, Tikal and Sticks keep running and Rouge, Omega, Cream, Silver, ESP Silver, Metal Sonic and Mephiles hover above the ground.
 * The Ring Boost acquired by using Chaotix Type characters may be a nod to their Team Blast Chaotix Recital from Sonic Heroes which awarded them with rings for every enemy destroyed during and shortly after using the ability.
 * The Animal Bonus the Rose Type gets may be a reference to Amy risking her life to protect and reunite the Flicky with his family in Sonic Adventure.
 * The enemy bonus awarded to Mech-type characters is a reference to E-123 Omega's quest for revenge on Dr. Eggman and his creations and Metal Sonic twice betraying Eggman in attempt to be the sole destroyer of Sonic, even going as far as sabotaging his own machine to have better gear in Sonic Free Riders.
 * Halloween Rouge is wearing the costume from her Sonic Channel wallpaper for 2014.
 * While Omega's artwork correctly places the "Ω" symbol on the front of his left shoulder, the symbol is positioned on the front of his right shoulder on his gameplay model.
 * Vector's dash attack is equal to his Head Slide ability introduced in the Mario & Sonic series, which is not surprising considering several developers from Sega Sport R&D, the developers behind said series, are listed in the credits for Sonic Runners.
 * This is the third game that uses profanity, because Knuckles says "damn" on a few occasions, and Zazz says that he will send Sonic into "Hell" during his event. The first was Sonic Adventure 2, in some of the song lyrics, and the second was Shadow the Hedgehog.
 * While technically not used in a profane way, Sonic says "Open the gates to Hell" in Sonic and the Secret Rings.
 * The canonicity of Sonic Runners appears to be dubious at best, but it appears to specifically follow the canon of the handheld versions of multi-platform Sonic games. This is evident several times, such as as Mother Wisp being mentioned; Sonic and Tails only encountered her in the DS version of Sonic Colors. However, the game's event-exclusive episodes are equally evident in being non-canon due to some companions being characters from certain games that endings imply Sonic will never meet again, such as Chip, and Sonic not knowing who Merlina is, despite meeting her in Sonic and the Black Knight. Even more curiously, Sonic does not recognize Erazor Djinn or King Shahryar despite the characters implying that the events of Sonic and the Secret Rings have taken place.
 * Likewise, ESP Silver's description implies that the bad ending was somehow canon in a similar way Blaze remembers "Crisis City" in Sonic Generations.
 * While Mephiles' existence could also count for that, Solaris's flame could've been a separate entity enough that blowing out the flame may not have destroyed Mephiles, but just gave him no reason to leave. However, his body is only formed after copying Shadow's shadow.
 * Sonic Runners makes numerous grammatical errors, the most prominent being that the word "get" is used in place of "go" (e.g. Sonic exclaiming, "Let's get after them!", instead of "Let's go after them!").
 * The game appears to be heavily based on Sonic Heroes, Sonic Colors, and Sonic Lost World, in terms of plot, characters, gameplay, and zones.
 * This game's menu reuses sound effects from Sonic Free Riders.
 * Shadow, Rouge, and Metal Sonic are the only playable characters so far not to get any new artwork for Sonic Runners. Instead, existent artwork is reused, but their arms and legs are shortened to fit the game's style.
 * Two pieces of artwork for Silver and one artwork for Omega are reused in a similar manner.
 * However, most poses used for Blaze, Big, Cream, Classic Sonic and Tikal are based on older artwork for these characters.
 * Team Sonic and Team Chaotix are the only teams from Sonic Heroes where all three members were converted into the same personality type.
 * Silver, Cream and Big are the first characters to be purchasable, followed by Amy and then Espio, Charmy and Vector.
 * The Chaotix are the only characters to be featured three times on the Premium Roulette before the update to v2.0.0.
 * Blaze is the first female character to be a Power type.
 * Silver is the first character to be part of two different teams, and the first to have a costume that changes his formation.
 * Blaze and Amitie-Style Amy's personality Type is not Rose, but "Lady" in the Japanese version of the game.
 * Though that may have changed in v2.0.0, as Blaze now gets the same animal boost as regular Amy.

Videos
Official trailer = Gameplay trailer = Launch trailer =