Bonus Stages (ボーナスステージ Bōnasusutēji?), also referred to as Mini Games, are extra, optional minigames in the Sonic the Hedgehog series, in which the player usually enters a different type of Stage with a different gameplay style. Bonus Stages are usually meant as a place where the player can collect Rings, points, extra lives or other items when passing through a Zone. Each game features a different way of entering a Bonus Stage, such as such being transported to one after collecting a certain amount of Rings, finding hidden Giant Rings or simply passing through the regular Zone. Bonus Stages and their gameplay styles vary between each game, as they feature many different gimmicks such as gumballs, slot machines and other types of minigames.
Bonus Stages are not to be confused with Special Stages, as the objective of the Special Stages is for the player to collect something in order to obtain a Chaos Emerald. Regardless, some of the Special Stages have retained the same role as Bonus Stages in several games.
Sonic the Hedgehog Spinball
In Sonic the Hedgehog Spinball, there are four different Bonus Stages, all of which take place inside a regular pinball cabinet. In this game, the player can play three Bonus Stages after passing through the regular levels, as the fourth level only becomes playable if the player has collected all the Rings from the three previous levels. When playing the Bonus Stages, Sonic himself can be seen playing the pinball table in the reflection of the windows in the background.
Each Bonus Stage has its own requirements for gathering more points to the total score. When playing, the player has three pinball balls to use during the Bonus Stage. Completing them will reward the player with "Rising Jackpot".
Sonic Spinball (8-bit)
In Sonic Spinball (8-bit), there are three different Bonus Stages that the player can enter in the same way as in the 16-bit counterpart game. Here, however, Sonic appears in the pinball sections and is able to find treasure boxes with points, Rings, extra lives and Continues.
Sonic the Hedgehog 3 & Knuckles
Sonic the Hedgehog 3 and its add-on continuation Sonic & Knuckles have three different Bonus Stages, which the player can enter via a Star Post when they have a certain number of Rings in their possession. While Sonic the Hedgehog 3 only features one type of Bonus Stage and Sonic & Knuckles features two, the locked-on version of the game, Sonic the Hedgehog 3 & Knuckles features all three Bonus Stages. Each Bonus Stage's gameplay and purpose are different. Sometimes, if this stage is accessed by a glitch, rather than saying "Bonus stage", the title card will say "Dolius Stage" instead.
In Sonic Labyrinth, a hidden Bonus Stage can be entered by finding the closed door with "BONUS" marked on it in Labyrinth of the Sea. The player has to enter a cannon to be launched into the direction where the door is located. After entering the Bonus Stage, the player can collect a huge amount of Rings within 30 seconds, where each Ring adds 25 Rings to the score. After clearing the Bonus Stage, the player obtains the sixth Chaos Emerald and can clear the game with the good ending.
In Knuckles' Chaotix, there are hidden Giant Rings set around in each Stage which can transport the player into the Bonus Stage if they have 20 Rings. Here, the player gets transported into a different dimension that serves as the Bonus Stage, in which Combi partner does not appear. In these Bonus Stages, the player falls down an endless void where numerous power-up boxes float around. By touching certain power-up boxes, the player can collect Rings and points. If they run out of Rings or hit an Exit box, however, the player is sent out of the Bonus Stage.
Sonic Advance 3
In Sonic Advance 3, there are two types of minigames available, which the player can participate in by finding Transporters within each Zone Map. In the first minigame, the player has to press one of the five switches that lights up on a large capsule as quickly as possible to earn as many points as possible, and in the second minigame, the player has to destroy all enemies within the area. Depending on how long it takes them to complete these minigames, the player is rewarded with a certain number of extra lives.
Sonic Runners Adventure
In Sonic Runners Adventure, Bonus levels are extra levels where the player can obtain additional Rings. These levels can be entered by collecting a Bonus item and then finishing the level in which it was found. In each Bonus level, the playable character flies through an obstacle-free space for a short time, during which they can pick up Rings from various clusters.
The Bonus Stages return in Sonic Mania, where they can be accessed in the same way as in Sonic the Hedgehog 3. They are functionally identical to the Special Stages from Sonic the Hedgehog 3, Sonic & Knuckles and Sonic the Hedgehog 3 & Knuckles, requiring the player traverse a small spherical planet, collecting blue spheres and Rings while avoiding red spheres. Unlike previous Bonus Stages, the award for successfully completing of a Bonus Stage in Sonic Mania is a medallion (silver for completion and gold for a "Perfect" completion).
In the Encore Mode DLC of Sonic Mania Plus, the Bonus Stages resemble pinball machines. In these stages, the player can choose prizes from a machine resembling the Combi Catcher from Knuckles' Chaotix. Acquiring items such as the Flame Shield grants the player the ability to use the item during their playthrough. The same is true when acquiring other characters for the player's party. Collecting an Eggman-shaped bomb does not grant the player anything.
- A screenshot from the 1992 Sega Summer Catalogue shows that Sonic the Hedgehog CD was originally meant to feature labyrinthine levels, which could possibly be scrapped Bonus Stages. These levels are somewhat reminiscent of Special Stages from the original Sonic the Hedgehog.
- Sonic the Hedgehog Spinball, Sonic Spinball (8-bit), Sonic Labyrinth and Sonic Runners Adventure are the only Sonic games that have Bonus Stages but not Special Stages.
- Certain Special Stages in the Sonic the Hedgehog series do not focus on finding Chaos Emeralds, but rather on collecting points, Rings, extra lives and Continues like in Bonus Stage. Some examples include the 8-bit version of Sonic the Hedgehog and Sonic Blast (if the player enters the Special Stage in the first Act of the Zone) and Sonic Heroes (if the player decides to enter the Bonus Challenge).