Space Intruders

Space Intruders is an early Space Invaders clone for the TRS-80.

The player controls a small ship at the bottom of the screen which can only move left and right. The ship fires vertically at invading aliens, which move left and right, while progressively speeding up and moving to the bottom of the screen. The aliens will fire selectively at the player, and if hit, their ship is destroyed. 3 blocks at the bottom of the screen provide a safe zone, but will slowly be destroyed by enemy and friendly fire. If all aliens are destroyed, the player advances to a more difficult wave. The player has 3 lives, and when all are lost it's game over.