I have my doubts that SC can cope with a fully fledged tile mapped game. Maybe Mike can prove us wrong.
I tried using SC to scroll tiles, but in the end I opted to use the native blitz drawblock command, and then used SC to put the sprites on top. It seems to work quite well, and the speed is ok too. Obviously using the blitz draw commands dont support alpha, but SC sprites on top do. You can see some of the results in an old beta...
http://www.urbaninteractive.net/HighWayBeta.zip