1982 Sinclair Research (UK)
by ICL
This little BASIC game by ICL is a different way of playing Space Invaders.
You control the cannon on the left side of the screen, the cannon moves from time to time independently of your will. Your job is to type a number between 10 to 60 that corresponds to the firing velocity, although I think it would be more accurate to talk about angles.
The invaders are on the right side of the screen, quietly, just like sitting ducks.
It's obviously a short longevity game, but still it as it's challenges. You have to play several times in order to understand what are the right angles and when the cannon shifts place you have to reorganize your position again, because the same numbers will have a different result. Cute.