Use the Scag keys (Shift, Control, Alt, Alt-Gr) as action buttons (jump, attack, special, etc) and have fun jumping. Older PC games used to do that instead of using Space for jumping. I have a copy of A Bug's Life on PC and it uses Shift to jump. Incidentally, it also uses Control for throwing things and Alt for changing the colour of seeds (yeah it's weird). Also C for camera.