Terra Force is a basic shoot ’em up, inspired by Galaxians and Snake (which had already inspired the first Firebird Silver release, Snake Bite for the Commodore Vic 20).
The gameplay is simple. Hit the alien at the top of the screen five times before the Earth or the Moon are destroyed. Alien Marauders move gradually down the screen (a la ‘Snake’) and if they touch the player’s ship, then a life is lost.
To create difficulty levels, the player can choose a game speed (from 1-5) before they start.