Move with the arrows or WASD. Up jumps, and in one-sixth gravity you'll be up there a while. Press up again in the air for a thruster burst, steered with left and right. Hold down as you press it to dive instead: that's how you get back down onto someone. Hold down to crouch, or to fall faster.
Light J, Heavy K, Special L. (Or Z X C.)
Specials: Special alone, forward + Special, and down + Special. Each fighter has three. Super: Heavy + Special together when the meter's full.
Block by holding away. Low attacks need a crouching block; jumping attacks need a standing one. Throw: Light + Heavy up close. Press them back to break a throw.
Down-forward + Heavy is an uppercut, for people who jump at you. Tap forward twice to dash.
Hit a light, then cancel into a special before it ends: that's a combo. Knock someone hard into the dome glass and they bounce.