This is lot harder than it sounds and not very straightforward at all.
Move using
and shoot by moving the
in the direction you want to fire. The 'enemy' is any blob that isn't you. If one of your bullets manages to hit an enemy, it'll die and you'll get the achievement.
I discovered this purely by chance and felt that I should pass it on to stop anyone else going through the agony of trying to work out what the hell they're supposed to do to meet the crazy requirements of this achievement.
Good luck!