The classic Defenders (Atari 2600 and other platforms) but then in a first person 3D perspective.
This game is to be run with a 16K expansion module.
You fly over a planet and have a proximity radar indicating where (left-right) an enemy is. Your radar can show false hits when meteorites fall down.
The enemies go down and you get points (250) if you shoot them before they reach the ground. The enemies will shoot at you and you will have to try to prevent being hit. If an enemy reaches the ground and can fly up and away again you loose points (50). You have a shield which can take take 10 hits.
With either one of the keys q-t moves you left-down. y-p right-down. a-g left-up, h-newline right up. z-m shoots the laser. Using two keys at once allows you to move non-diagonal.
