Use use up and down arrow keys to move forwards and backwards. Use the right and left arrow keys to turn. Press S to throw a punch in front of you. Press Space to toggle Flashtime (aka slow-mo mode). Run around in a circle to charge up a lightning shot - once the number at the bottom reaches 100 you can release. (run in a circle by holding up and right/left arrow keys). Press P to toggle Phase mode, where you can run through enemies and are invisible.
There is only one kind of enemy for now, a Robber, which looks and moves towards you but deals no damage. They will actually look where you were a split second ago, which can be lengthened with Flashtime. It's fun. Funny thing I added: if it comes down to one last Robber, they start backing away since all their comrades are, well, defeated.