Star Defender II is a top-down horizontally scrolling shooter game. The player with his single spaceship must move left and right, firing on the enemy ships that appear. Successful destruction of enemy vessels increases the score. Some enemies drop power-ups when destroyed which include upgrading the primary weapon, granting missiles (regular and homing) for the secondary weapon, time freeze, nuclear bomb which destroys everything on the screen and a shield which protects the player for a short time. Without the shield, enemy fire will destroy the player's vessel and cause them to lose a life