Exeller is the main antagonist of the game, and doesn't seem to stop killing anytime soon. Green rings can save you from a bad choice, red rings can send your character into an illusion, and black rings can save your character in Solo endings from being killed by Exeller when sent to a location. The game also has a choices system, which the player can choose a choice that either saves the character, or ends up killing them. Eggman, who has a different gameplay style than Tails and Knuckles. The game is powered by Not So Simple Sonic Worlds, which tries to imitate the genesis gameplay of the classic Sonic games.
You are free to download it from the Game Jolt website. The current public version of the game is as you would expect.