Cosmic Defender by 2DPlay [zoom]
Move with the arrow keys. Space key to fire. b key for smart bomb which kills everything on the screen. d to teleport, which is useful since the aliens are relentless kamakaze maniacs.

Stop the aliens from abducting your citizens. When you stop an abduction, make sure you catch the citizens before they fall to their doom (by flying into them.) You can bring them back to safety by flying down to the bottom.

This game appeared on many of the early console systems. There is probably thousands of freeware PC versions of Defender. Because the ship moves very fast and drifts from the momentum, this version of the game is actually much more difficult than most.