Your ship constantly runs from lef to right, slowly descending. Below are some buildings. The player must press space to drop bombs and destroy the buildings before they are so low that they just crash into them.
Gameplay for the main part is complete. There was to be a boss section which would involve a genuine bitmap background and Lemmings/Worms style destruction and I seem to have fully or near-fully coded that but never incorporated it.
You`ll only have to hit the Space key in order to shoot at the exact right moments.