Sonic’s sidekick Tails had a few solo adventures in game systems of the past.
The first one was Tails and the Music Maker on the short-lived Sega Pico.
Here’s a video of that done by NintendoComplete.
However, more people know of the two Game Gear titles starring the flying two-tailed fox.
First one is Tails Skypatrol, and the second is Tails Adventure.
Here are videos of those games being played, both of which provided by YouTube channel Amy Rose Longplays.
Yeah, it wasn’t just Knuckles who had his own game (Knuckles’ Chaotix). Nor Shadow much later on. Who knows which of Sonic’s friends (or rivals) might be next to get their own game?