This game is a sort of Robotron with lots of added extras. There are a number of screens, each one wth a different pattern concentration of the different kinds of aliens. The aliens initially start off stationary, but start to move after you have shot a few.
The aliens come in a number of different types, each with their own personality. Some types are invulnerable until they start moving, some seem to home-in on you with lasers and others are just awkward.
A screen is completed by clearing out all the nasties with your gun. Four directional movement is used with the gun firing in the direction that you were facing, rather than the complex Robotron controls.
The options are also quite comprehensive, there is the ability to set one of five different speeds - the fastest speed is obviously for Electron users as it is pretty impossible otherwise.
One annoying thing is that the speed always resets to the default setting at the end of a game necessitating going through the selection procedure again.
Altogether a reasonable game, though whether it is worth nearly £8 is up to personal taste.