Note to windows users: you can change the controls
(the button is in the lower left marked "change controls")
Nice little game -- the customization is a nice touch. Two major changes would make it even better: 1) don't lock out any keys (for example, if you try to use the arrow keys for one-player mode it says "already defined") and 2) add more levels -- just have it move through the maps and increase the difficulty level -- you've already done most of the work; just automate it a bit.