1. Cosmic invaders will appear and disappear.
2. Zap invaders that match the one you saw n steps ago.
3. Start at Level 1 (1 step back). Level increases as you progress.
4. Correct zaps increase score, mistakes cost lives.
5. Game speed increases with each level.
6. Collect power-ups for bonus effects!
7. Game ends when you run out of lives. Good luck!