Sonic Adventure was one of the launch games for the Sega Dreamcast and a real system seller, like Mario 64 before on the Nintendo 64 as example.

It had graphics not seen before, especially not in a Sonic or Platformer game and also this awesome Emerald Coast stage:

Sonic Adventure Screenshot

…where that Orca / Killer whale hunts Sonic and destroys parts of the stage.

Joel Sousa from Portugal draw that part of the game very well here as you can see.

Sonic Adventure is an really awesome game and this artwork illustrates it very well!

Sonic Adventure Art