Fun with Thing Thing continues and gets even better. Even more enemies and modes means even more non-stop action.

Aim and shoot with your mouse
A and D or Left and Right: Move left and right
Shift: Run
W or Up: Jump, hold it or tap twice to double jump. Do this while moving backwards and you'll do a backflip.
E and NumPad 0: Cycle forward and back through weapons
P: Pause