Main Series:
* Sonic the Hedgehog 2 (1992): This game is where Super Sonic made his debut! You unlock him by collecting all seven Chaos Emeralds.
* Sonic the Hedgehog 3 & Knuckles (1994): Super Sonic returns, with a revamped design and abilities.
* Sonic Adventure (1998): Super Sonic returns, with a new design and abilities.
* Sonic Adventure 2 (2001): Super Sonic is playable in the "Hero Story" mode. You unlock him by collecting all seven Chaos Emeralds.
* Sonic Heroes (2003): Super Sonic is playable in the "Team Sonic" story mode. You unlock him by collecting all seven Chaos Emeralds.
* Sonic Unleashed (2008): Super Sonic returns, with a new design and abilities.
* Sonic Colors (2010): Super Sonic returns, with a new design and abilities.
* Sonic Generations (2011): Super Sonic returns, with a new design and abilities. You can unlock him by completing all the stages in the game.
* Sonic Lost World (2013): Super Sonic returns, with a new design and abilities.
* Sonic Frontiers (2022): Super Sonic is playable.
Spin-offs:
* Sonic & Knuckles (1994): Super Sonic is playable in the "Knuckles' Chaotix" mode.
* Sonic Mania (2017): Super Sonic is playable.
* Sonic Mania Plus (2018): Super Sonic is playable.
* Sonic Forces (2017): Super Sonic is playable in the "Modern" stages. You unlock him by collecting all seven Chaos Emeralds.
* Sonic Rush Adventure (2007): Super Sonic is playable with a new design and abilities. You unlock him by collecting all seven Chaos Emeralds.
* Sonic Boom: Rise of Lyric (2014): Super Sonic is playable, with a new design and abilities.
Other appearances:
* Sonic the Hedgehog (2006): Super Sonic appears, but is only playable for a brief period in the game's ending.
* Sonic Rivals (2006): Super Sonic appears as a playable character, but you must unlock him by collecting all seven Chaos Emeralds.
* Sonic Rivals 2 (2007): Super Sonic appears as a playable character.
* Sonic Pinball Party (2003): Super Sonic appears as a playable character.
It's worth noting that some games also have a "Super" transformation that's not necessarily Super Sonic, but a similar power-up like "Hyper Sonic" (Sonic Rush) or "Super Shadow" (Sonic Adventure 2).
Let me know if you want more details about a specific game or have any further questions!