Extra modes
The game has several extra modes to unlock, which can be accomplished by playing a game, the first of which can be unlocked by scoring at least 1000 points. The more points that are scored during a game, the more modes will be unlocked. Note: Erasing the high scores will also erase the Y. A. S. I. screen configuration and the extra modes. The modes are as follows:
A: Regular Y. A. S. I. game (no features)
B: Guided missiles
C: Moving bunkers
D: Guided missiles and moving bunkers
E: Cloaking invaders
F: Guided missiles/cloaking invaders
G: Moving bunkers/cloaking invaders
H: Guided missiles/Moving bunkers/Cloaking invaders