Valvo is a boardgame (although its authors also define it as a strategy game) that has many things in common with Backgammon.
In Valvo two players compete. You must make each of your moves with a lot of strategy and use tactics, and also show your intelligence before moving any of your pieces (both to win and also to block your opponent from winning).
You also have up to 6 difficulty levels in Valvo, and some of them are very complex. Valvo is also completely free.