You are playing as the raptor, and you are fighting the Pachycephalosaurus. You can attack in melee with the s key, move left with the a key, move right with the d key, and jump with space. If you hit the Pachycephalosaurus at the end of a jump, you jump on its back and it takes damage while it is defenseless, while if the enemy hits you, you take damage and are bashed into the side of the screen. Sorry, there may be a few bugs, and the ai is pretty good.