Player 1: WASD, Player 2: Arrow Keys, Player 3: 8 4 5 6 (Numpad recommended), Player 4: IJKL
This is my one of my first projects experimenting with multiplayer, sometimes for some reason it doesn't work with some people (I have a feeling you need to be a scratcher for it work correctly). I hope you enjoy it and it inspires more people to make online multiplayer games (It might seem hard but its really simple if you know what your doing.).