From game instructions
The deep space exploration ship DARWIN 8 has been invaded by hostile alien robots. As the last surviving crew member it is your job to deal with the problem.
The robots are all armed with laser guns and each group has at least one positronic generator from which they draw their power.
Your rifle will only stun the robots while there is still an active generator on the screen, so destroy these first and then you can kill the robots. Complete each level as fast as you can to pick up the time bonus, but be careful not to walk into walls or barriers as these have been electrified and contact with them is fatal.
User summary
An extended re-implementation have been made in 2010 by RGCD called Robotz DX. DX have a slightly improved graphics and sound and a few gameplay changes.