Resident Evil Gaiden is a Resident Evil game for the Game Boy Color. It is non-canon, as its plot is contradicted by the main series in key parts and its events are ignored. The game features three playable characters and consists of exploring areas, collecting items and combating enemies in the process. Unlike previous entries in the series, Resident Evil Gaiden assumes a top-down perspective for the environment portions that, upon approaching an enemy, changes to a first-person combat mode with a reticle constantly moving to the left and right. To attack, the player has to press the action button while the reticle is in range of the enemy.

It's believed that Umbrella, the creators of the deadly virus that wiped out Raccoon City, has developed a new Bio Organic Weapon on a cruise ship called the Starlight which is on its way to Europe. One S.T.A.R.S. member Leon S. Kennedy was sent out to destroy the weapon, but the team have been unable to contact him since he arrived at the ship.