Sonic Riders

The game's got a quite a few modes of play, a few of which support up to two people. There's a story mode, though there isn't much of a story. Its vaguely comprehensible plot points involve Eggman setting up an air-board tournament for Sonic, Tails, Knuckles, and his various cartoonish enemies. The winner gets a bunch of Chaos Emeralds, which unlocks long lost Babylon. Since he's a super villain, it makes sense that Eggman eventually steals all the Chaos Emeralds after the story mode's fifth race, prompting a sixth race amongst Babylon's ruins. In addition to the story for Sonic and friends, there's a separate one for his enemies, though the tracks are quite similar. There's also Free Race, Time Attack, and World Grand Prix modes, a Tag mode, and Race and Battle stage variations of a Survival mode.