The arsenal is the weapons you have available. To use a weapon click the number on the keyboard. The Laser bolt does require you to aim with the mouse. The Clone Trooper walks across the battle and has a chance to either kill a battle droid or be killed by a battle droid. Red Squadron will nuke the battle field killing all battle droids. The Fighter will swoop down to eliminate droids but does have a small chance to be eliminated by the droids. The Jedi you can take control of with the arrow keys to move and the space bar to attack the Jedi can't be killed but will be removed from the battle field after 60 seconds. Your objective is to fight against the oncoming battle droids and stay alive.