Super Smash Bros. Ultimate

Super Smash Bros. Ultimate (大乱闘スマッシュブラザーズ SPECIAL) is the fifth installment in the Super Smash Bros. fighting series. It is a 3D on a 2D plane fighting game for the Nintendo Switch developed by Bandai Namco Studios and Sora Ltd. and published by Nintendo. It was released on 7 December 2018.

Sonic the Hedgehog, along with every other character from the previous installments, returned along with a batch of new characters. This game also supports amiibo, including the Sonic amiibo.

Development
The first teaser for Super Smash Bros. Ultimate appeared during a Nintendo Direct on 8 March 2018. Back then, it was only known by the title Super Smash Bros.. It was formally announced during Nintendo's Nintendo Direct presentation at E3 2018.

Responsible for the development of Super Smash Bros. Ultimate are Bandai Namco Studios and Sora Ltd., who were behind the development of Super Smash Bros. for Nintendo 3DS and Wii U, with Masahiro Sakurai serving as the director. The intention of Sakurai's for Super Smash Bros. Ultimate was to include every possible character from previous Super Smash Bros. games, which he knew would be both a complex problem for both development and licensing. He also intended to speed up the game by adjusting the characters' abilities. Sakurai knew that Super Smash Bros. Ultimate was both a core title for Nintendo, and that it has a dedicated playerbase that he did not want to disappoint, and believed that he needed to complete these goals to satisfy both groups. Nintendo announced that David Hayter reprises his Solid Snake voice-over for Ultimate.

Inclusion of Sonic the Hedgehog
On 12 June 2018, it was announced on the E3 Nintendo Direct that every single playable character from the past four games would return. Among them is Sonic the Hedgehog, marking his third appearance as a fighter in the series. Like in Super Smash Bros. Brawl, Sonic must first be unlocked in order to play as him. To unlock Sonic, the player must complete Classic Mode as Mario, before defeating Sonic in a one stock battle.

In addition to Sonic's inclusion as a fighter, Green Hill Zone from Super Smash Bros. Brawl and Windy Hill from Super Smash Bros. for Nintendo 3DS and Wii U make a return. Shadow the Hedgehog returns as an Assist Trophy, slowing players down using Chaos Control with the green Chaos Emerald. Knuckles the Echidna will also make an appearance as an Assist Trophy and will attack opponents by punching them, using the Homing Attack, or dig underground and use a powerful uppercut when summoned.

Spirits
Various other Sonic characters also make an appearance in the form of Spirits. Spirits are power up characters that can give fighters a boost in battle. They are either a Primary Spirit or a Support Spirit, can be one of five types, (Grab, Shield, Attack, Balanced or Neutral) and can come in one of four classes. In order from weakest to strongest class: Novice (★), Advanced (★★), Ace (★★★), and Legend (★★★★). All currently known Sonic Spirits include:

Music
The following is a list of music from the Sonic series included in the game. There are 20 in total:
 * "Green Hill Zone"
 * "Scrap Brain Zone"
 * "Emerald Hill Zone"
 * "Angel Island Zone"
 * "Sonic Boom"
 * "Super Sonic Racing"
 * "Open Your Heart"
 * "Live and Learn"
 * "Sonic Heroes"
 * "His World" (instrumental)
 * "Seven Rings In Hand"
 * "Escape from the City"
 * "Knight of the Wind"
 * "Reach for the Stars"
 * "Rooftop Run"
 * "Wonder World"
 * "Windy Hill - Zone 1"
 * "Lights, Camera, Action!"
 * "Fist Bump"
 * "Sunset Heights"

Trivia

 * This is the first Super Smash Bros. game since the original Super Smash Bros. to not be announced alongside new hardware.
 * Moreover, this is the first time since Super Smash Bros. Melee that a Super Smash Bros. game has not been announced years in advance.
 * This is the first Super Smash Bros. game to not feature the involvement of Satoru Iwata as he passed away in July 2015.
 * The release date of Super Smash Bros. Ultimate falls one day after the late Satoru Iwata's birthday, 6 December, which was also the release date of Super Smash Bros. Wii U in Japan.
 * This is the first Super Smash Bros. game since Super Smash Bros. Melee, the second installment of the series, where no veteran characters were cut.
 * This is the first Super Smash Bros. game where the English voice for the Announcer has not been changed from the previous game.
 * This is the first Super Smash Bros. game since the original Super Smash Bros. to feature 2D illustrations on the box art.
 * With Sonic's inclusion in this game, he is the only third-party character to appear in three Super Smash Bros. titles.
 * This is the first Super Smash Bros. game to have none of its newcomers as starter characters.
 * Sonic's default head icon in Super Smash Bros. Ultimate bears a striking resemblance to several logos and icons in the Sonic series, namely the logo for Sonic Team.
 * Sonic and Knuckles were both featured on the Super Smash Bros. Ultimate blog on 2 July 2018.
 * So far, Sonic is the only third party character with more than one stage representing his series.
 * This is the first Super Smash Bros. game in which two characters from the Sonic the Hedgehog series appear as Assist Trophies.
 * This is the first Super Smash Bros. game to have a vocal theme song in both English and Japanese.
 * Unlike other installments in the Super Smash Bros. series, Sonic actually takes a bit of damage if he falls in any body of water, which is a nod to his inability to swim.
 * This is the first Super Smash Bros. game to not feature Trophies since the original Super Smash Bros.
 * Part of the on Twitter, with six days left before the game's release the official Japanese Sega Twitter posted a Tweet representing Sonic's inclusion in the game.
 * Though likely unintentional, it is possible for a fighter to summon Knuckles as an Assist Trophy in the Green Hill Zone stage, even if he is already running through the loop in the background, resulting in two different versions of Knuckles on-screen.
 * Aside from Sonic the Hedgehog, Sega's other franchises (Bayonetta and Virtua Fighter) make an appearance in Super Smash Bros. Ultimate.  The titular character from Bayonetta returns as a playable character while Akira Yuki makes an appearance as an Assist Trophy. Joker, from Persona 5 will appear as a DLC character in the future.
 * Coincidently, Joker's outfit is one of the available costumes for the Avatar in Sonic Forces.