Defender II is a side-scrolling shoot 'em up for the Atari 2600 in which the player pilots a spaceship to protect human colonists from alien attackers. The player must rescue abducted humanoids, destroy enemy ships, and avoid obstacles across sixteen wave sectors. Notable for its fast-paced action, multiple ship lives, smart bomb and invisibility power-ups, and being a rebranded version of the arcade title Stargate released in 1988.