Steam Droid Make your way to the end of the level while saving the enslaved droids. On your way there will be a lot of enemies and traps who will try to get you which you mustn't allow. Use your gun and its destructive power to put a stop to them. After you kill them they will drop green balls which you collect and use as an upgrade tool for your armor, gun and other accessories. There are 14 levels and a boss at the end. Power yourself up to become strong enough to overcome whatever awaits you on your rescue journey.