This is quite an accurate copy of the original in layout, and has the six cities and three laser bases. Each base has its own fire button. Although the keys are fairly well laid out, individual base firing is rather difficult with a total of 7 keys. Because of this, I welcomed the computer-aided firing option which allows you to fire from the nearest base with one key press. This has a slight bias to the outer bases to avoid draining the centre one. The Kempston option greatly improves playability. Graphics are quite good and colourful but not very smooth. The explosions are quite different from the original, being clouds of smoke. Good sound with a nice frying noise adding to the feel. There are planes and satellites, also smart weapons (move straight down). These latter are a little jerky due to character position movement. Overall, a reasonable game.
This has a two-part load - you input whether you want to use a Kempston joystick. The first thing you notice about this version is its sound, very good effects. The cross hair movement is block and not smooth - not actually a disvantage as the explosions are realistically long lasting. This version has several features which the Softek one doesn't like alien craft and satellites and intelligent missiles which hover over your explosions until it's safe. Also three missile silos and a useful auto-fire select. A game that is a good copy of the arcade original and I think is the second best version for keyboard use.