Fire Barrel (also known as Air Assault) is a rather obscure vertical-scrolling Shoot 'em Up made by Irem in 1993. The game bears many similarities to Raiden, such as weapon types and the overall feel of it. Though it barely resembles it, the game is meant to be a sequel of sort to Air Duel.
- Follow the Leader: To Raiden.
- Giant Mook: Several, such as large helicopters and tanks.
- Homing Projectile: The Homing Missile weapon, which homes in on enemies but does less damage than the dumbfire Megaton Missile weapon.
- More Dakka: The Vulcan Gun weapon.
- Mutually Exclusive Powerups: The main weapon powerups, as well as the Missile weapon powerups.
- Nintendo Hard
- Non-Indicative Name: The Grenade Weapon shoots spreads of rockets in 5 directions.
- Sequential Boss: The Final Boss.
- Smart Bomb: But of course.
- Spread Shot: Two kinds: The Wing Gun and Grenade. The Wing Gun shoots up to seven crescent projectiles forwards, while the Grenade shoots rockets forwards, to the sides, and to the rear of the player.
- Wave Motion Gun: The blue weapon (Graviton Laser). Seems like an expy of the blue laser weapon from Raiden.