Invader is a vertical scrolling shoot-em-up for the Nintendo Game Boy Advance. There are 8 levels to shoot through each ending with a end-boss. The player can select from 2 different ships each with specific features. Enemies leave coins that can be spent in the Shop, where upgrades such as weapons, extra lives, and credits are available for purchase.

Join the fight for freedom in Invader! Your mission: defend the human solar system, Alpha Nerconis, from the evil swarm, a seemingly unstoppable alien force bent on total domination. Grab the controls of either a Rygotian or an Ikaben ship and get ready to join the fast-paced and explosive battle. Only you can stop these invaders, and save the solar system.