Tic-Tac-Toe-like games is a large class of finite 2-player games with complete information and no chance moves. Randomness plays an auxiliary but crucial role in the theory. This is quite surprising since both the games and the optimal strategies are deterministic. How can randomness then enter the story? Well, this is what we call the ``random game principle", and it says in a nutshell that in many ``complex" games, the outcome between two perfect players is the same as the ``majority outcome" between two ``random generators". Warning: this doesn't mean at all that a random counter-play is effective against a clever opponent. We also mention two other principles: the ``neighborhood principle" and the ``fractional mirror image".