Defense Command is the seventh and final Bill Hogue programmed arcade game that Big Five Software released for the TRS-80.
Not directly inspired by any arcade game, although perhaps partially inspired by Defender, Defense Command challenges the player to defend a supply of fuel cells arrayed across the bottom of the screen. The player's Laser Command Base moves back and forth across the bottom of the screen shooting missiles at a non-stop onslaught of aliens. The alien ships swoop down from the top of the screen to try to steal fuel cells. The player must use careful aim as only one missile can be on the screen at a time.
If an alien grabs a fuel cell, it tries to escape off the top of the screen with it. If the player shoots an alien making off with a fuel cell, the fuel cell falls back to the bottom of the screen. The player's base must "catch" the fuel cell at the bottom of the screen, otherwise it will be destroyed by the fall.
For extra firepower, the player has AMB's (anti-matter bombs) that destroy all aliens on screen.
The iconic alien Flagship plays a role in Defense Command. Occasionally a Flagship will moves across the top of the screen. If you shoot the Flagship, a swarm of aliens is released.