Space Invaders
PLAY !

  Left arrow - move left
  Right arrow - move right
 
  Space - Fire missile
 
 P - Pause/unpause game 
 Q - Quit game 

Japanese company Taito had the inspired idea around 1978 that killing aliens was extremely good fun. So they invented a game called Space Invaders, lots of history then followed, some people got rich and so on...

It's a simple game with simple graphics, but it has one of the most vital assets for any computer game — gameplay. Modern games seem to forget this with their fancy "3D graphics" and "millions of dollars". All you need is a pointy green thing which shoots white stuff at a rampaging invasion of wobbling blobs. They don't make 'em like they used to.