The keys for movement are definable with the Preferences menu item.  The movements and actions which can be carried out are listed below.

forward - move one space forward
backward - move one space backward without turning around
turn around - turn around on the spot
left - turn 90° left on the spot
right - turn 90° right on the spot

fire - fire a bullet
map - toggles between normal view and map screen
scrambler - activate a scrambler