Buy
Could be interesting

Sonic Astral Generations is a fangame that seeks to give the opportunity to new levels that were absent in the 3 versions of Sonic Generation, with brand new Friends to save.

One day Big the Cat was going to fish on his favorite fishing river and he noticed that the river was polluted and all the fishes were gone! So he begin a quest to find the culprits and make justice
2002, the year Sonic 2099 was released on Windows. Made and self published by TGF Team, this action game is available for free.

Tails and the Quest of 100 Rings is a fan game created by Magnus Andersson (aka mightydillo). A demo was initially released publicly with one zone in 1997. It was only the second Klik & Play Sonic-based fan game to ever hit the internet. A completed version was released in mid-1998. A demo for this game was released in the Sonic Klik & Play Collection.

Tales' Epic Gang is a 2D Sonic the Hedgehog Fan Game with cartoony graphics and wacky characters.

The game aims to combine multiple mechanics from various Sonic games to offer a fresh and unique gameplay experience!

Sonic the Hedgehog XA is an open-source fan-game inspired by classic Sonic games from the Sega Genesis. It was built from scratch by a single person using the C language and PSn00bSDK and a lot of tools and scripts created for the sole purpose of building this game. Sonic XA is a game that runs on the PlayStation 1, so to play it, you will need to use an emulator or burn the game to a proper CD-ROM so you can play it on your home console.

Stop Eggman's Control over the seasons on Eastside Island in Sonic Seasons!

A 2D Sonic fan game with an emphasis on quick and focused level design.

The Ultimate 2D Sonic Adventure!