Achron

How would combat change if you could foresee the future? If you could prevent your past mistakes from ever happening? What if your enemy could too? Achron is the first and only game to feature single-player and multiplayer free-form time travel. It is the world's first meta-time strategy game, a real-time strategy game where players and units can jump to and play at different times simultaneously and independently.

(Source: Project Homepage)