This game is best described as a vertical Defender without scenery or humanoids.
You fly your ship through various waves of different types of enemy ship that exhibit similar personalities to those found in Defender - i.e. there is a baiter-type, pods, swarmers, landers (except that they don't land!). There is also an added feature of an energy balloon; blast this twelve times and your firepower is increased.
Your armament initially consists of a laser system in the good old Defender style. Also the old favourites - smart bombs - rear their ugly heads.
A function carried over from the sequel to Defender - Stargate - has also been included, inviso-flight. This makes you temporarily invisible and immune to enemy attack.
The ship can go in four directions, and re-trace its steps to get a baddy that has been missed. You also have a long range radar scope to see what's coming up, and what's been left behind.
Altogether a reasonable game for the price, this is a lot better than some of the rubbish that has been turned out in the 'budget' category.