Co-op has been a staple feature of many Sonic games for decades now. These examples are the best of the bunch.

Shadow the Hedgehog is back with Classic and Modern Sonic in SONIC X SHADOW GENERATIONS, an all-new collection featuring two unique experiences! Play as Shadow the Hedgehog in a brand-new story ...

they're actually based on the fighting game Sonic the Fighters, the first 3D entry in the series. They're a fun set of credits, and in a pretty lengthy YouTube video, the person that made them ...

SEGA has released the Sonic Jam skin for Sonic X Shadow Generations, and the best part is, the skin is free for all players.

SEGA has announced that Sonic X Shadow Generations has now sold more than two million copies around the world.