Today Sega released The Murder of Sonic the Hedgehog, a visual novel now available on PC via Steam featuring the characters of the popular franchise.
While it's an April Fools' prank described as a labor of love by the Sonic social team, it's actually a real game that you can download on Steam and play it even got its launch trailer which you can watch below.
The Murder of Sonic the Hedgehog is set during Amy Rose's birthday on the Mirage Express (which comes with a conductor who is an obvious homage to the late Leiji Matsumoto's Galaxy Express 999). Sonic himself is the victim of a murder mystery game and everyone sets out to solve the case.
Of course, the game is not canon and it isn't developed by the Sonic Team albeit Sega's team mentions that they "strongly believe in the power of headcanon."
If you're more interested in real Sonic games (ok, this is real in a manner of speaking, but you know what I mean), Sega recently announced Sonic Origins Plus for PS5, PS4, Xbox, Switch, and PC. It includes the original Sonic Origins complement with Sonic the Hedgehog 1, Sonic the Hedgehog 2, Sonic 3 & Knuckles, Sonic CD, and adds 12 emulated Game Gear games, plus a few bits and bobs.