As to show my thanks to Peter and give more fun to Aurel, here is a slight mod to Peter's game.
Each time you start it will play a different music, well it is random from 3 choices, so you might hear the same one twice.
I modded the explosion and enemy blasts sprites. That is all.
I didn't have time to figure out how to make random music choice with each press of C to play again. Instead you have to restart the ufo3.exe file.
Updated Post, new version further down, so removed old attachment here.