TI Invaders followed the usual Space Invaders formula pretty closely with only a few minor differences.
For one thing, the Invaders were several colors, being red, blue and green. When the player's shot from their missile base collided with an Invader's bomb, their score would increase by one point (normally in Space Invaders games there is no score for an incident such as this). The remaining missile bases are encased in a large rectangle, which, once the player's missile base got destroyed, the action would freeze while the destroyed laser base would be moved into the rectangle and stored to the right side, then the next missile base in reserve would be ejected from the rectangle. If the player scores 10,000 points or a multiple thereof, one of the missile bases will be repaired.
Also, in between each Invaders wave, there is a bonus round where it is just the player vs. the UFO, which, each time the player shoots it, it decreases in size and starts heading in the opposite direction, but at a quicker pace than before.
There are two skill levels available, being "merely aggressive" or "downright nasty"; if the player chooses the latter, the Invaders are worth twice the points as on the easier level.
- Bottom row invaders--5/10
- Middle row invaders--10/20
- Top row invader--15/30
- Hitting Invader bomb--1 point
- Extra missile base--3,000 points
- Missile base repaired--one every 10,000 points
- Move laser cannon--left and right on joystick
YouTube video of the game