Dam Busters is really a version of Scramble, with a few innovations. You fly a plane over a mountainous landscape using the 'A', 'Z', 'Space' and 'Shift' keys. Enemy aircraft may be despatched using either your nose or tail guns as appropriate and these are fired using the 'Return' and 'Copy' keys.
Hostile gun emplacements, positioned at random intervals, take the occasional pot shot at you, which must be avoided if you're not to lose one of your five lives. The guns may also be bombed, using the 'Tab' key.
No surprises so far for Scramble-addicts, but every so often you find yourself flying over a lake, and this is where the game shows a few original touches.
A range-finder flashes up at the top of the screen and as soon as it shows zero you drop your bomb, which with any luck will bounce along the surface of the lake and destroy the dam at the end.
Altitude is also crucial, and to increase your chances of a hit you have to move up and down until two dots on the surface of the lake join together.
Then it's 'bombs away' - but the program warns you that the range-finder was developed in a hurry and therefore doesn't work all the time!