Base Invaders is a Space Invaders
clone. The gameplay is identical to the original, you control a ship that must shoot and destroy a batch of aliens known as invaders. There are six rows of invaders that must be shot, you must clear the wave to move on the next one. Every time the invaders move across the screen they move down and you must prevent them from reaching the bottom of the screen. The invaders will fire at you which you need to avoid, you can also choose to block their shots by firing at them. Every so often a saucer flays over the invaders which you can shoot to earn a points bonus.
You are aided with five bases which you can hide to avoid the invaders' shots but unlike most Space Invaders games they do not reset after the completion of the level.