For single player: Use single the arrow keys. Click m to use the mouse pointer. Click space to eat. Get the teleporting mouse. Click a to use the arrow keys again. You can only switch from arrow keys to mouse pointer once. For multiplayer mode: One person is the mouse one person is the cat. The mouse uses the WASD keys and the cat uses the arrow keys. The cat chases the mouse. When the cat gets the mouse, it wins.
None until I realize I could make the cat and mouse cartoon characters... There is a multiplayer mode. Hold T until the mouse stops teleporting for multiplayer mode. Click n to go back to normal mode. Arrow keys are harder than the mouse pointer.