How to play a Drill Invader. 1.Please touch a "start" button after reading an. Explanatory note. 2.Please touch a "Go" button, after a game screen. Appears. A game starts. 3.After formula UFO appears, please touch "←"" ". Button and move an attacker to just under UFO. 4.Please touch the "Attcker" button after making the. Answer of calculation using ten key.