Galaga 1990

[Geoff Canyon Rev]

Since the enemies' paths are pre-determined in this method, you can
determine whether a particular shot will hit an enemy at the time the
shot is fired. And vice versa, whether an enemy that you are planning
the route for will intersect any of the current shots on the screen.
It requires a bit of work, but it's (much) better than checking each
time you move the ship to see whether any of the shots have hit any of
the enemies.