A simple game using pygame
Initially a fighter ship at bottom and a fleet of alien ships covering more than a half of game woindow appears on the screen. The fighter shift can be moved left and right by respective arrow keys and can fire bullets using spacebar. The fleet moves towards the fighter ship at a steady rate. If the player manages to destroy all the ships of the alien fleet, next fleet appears that moves at a faster rate towards the fighter ship. If fleet hits bottom of the game window or hits the fighter ship three times, game is over.