Starcraft 1.5: Fusion is a series of totally converted Warcraft III custom maps designed to feel and play exactly the same as Starcraft. The project currently has single player and multiplayer maps designed and based on the original and newest Starcraft games.
Here is a screenshot I took of a battle between a small Terran army against an equal Protoss army. This will give you a quick look at how the 2 races look in a battle simulation shot. Unfortunately the Protoss army won quite convincing which I'm a little worried about.