This game has online co-op! And it works well. It's not like the Sonic 2 co-op, where Tails will just get left behind. You just have to tap a button to reunite Tails and Sonic. The online seems to be sturdy. I had a little bit of lag during the final Acts, but it never became unplayable. But don't expect to just find some rando online, because I don't think many people even REALIZE the online co-op exists. It's not even listed on the steam features blurb. Plus it's a million times better than Episode 1. Skip right to episode 2. And don't believe the people who say this game is "the worst Sonic game ever." It's FUN. And the music and level design are both on-point. The homing mechanism is a little bit broken, though. And there are several frustrating moments towards the end. But it's not a bad game, dammit. It's probably not worth a full $15, though. Or maybe it is, if you can find someone to play with.