Controls: Arrow keys / A,D to move, Space to shoot
Goal: Destroy all aliens before they reach Earth!
Power-ups: Rapid Fire (R), Shield (S), Multi-Shot (M), Extra Life (+), Score x2
UFO: Mystery ship at top = 50-300 bonus points
Bunkers: 4 defensive barriers that degrade
Bosses: Wave 5 = Mini-boss, Wave 10 = Mothership
Combo: +1 per consecutive hit, resets on miss, multiplies score!