Delta Patrol

Delta is a horizontally-scrolling shooter computer game origianlly released for the Commodore 64 by Thalamus Ltd in 1987. It was programmed by Stavros Fasoulas and the music was written by Rob Hubbard. The game was also released for the ZX Spectrum in 1990 as Delta Charge.

The player controls a spaceship and gains power-up points by destroying formations of enemies. However some enemy formations subtract power-up points for the player instead, so the player must take note of which formations to destroy. Periodically blocks containing the power-ups (higher speed, faster rate of fire) appear and the player can pick one of them up: The more points the player has collected, the more powerful are the power-ups that can be chosen. Unavailable power-ups are gray and kill the player if he flies into them, making them part of the obstacles in the game. The effects of the power-ups are lost over time and must therefore be regained. The player gets a choice between in-game music or in-game sound effects. There is also a high score table but no way to save it when the game is turned off.