Left and Right keys. I need to make some good ball physics to go with these. My ball physics are not realistic enough yet. I am trying to understand enough to get there.
Notice how the flippers shoot up fast but if you let go and press them again really quick they flip back up without having to go all the way down. Also notice that if you just barely tap left or right super quick, it barely moves the flippers (for flipper tip passes of the pinball from one side to the other).