Koutetsu Yousai Strahl (鋼鉄要塞 シュトラール, "Steel Fortress Strahl" - "Strahl" is German for ray, beam, radiation or stream) is a horizontally scrolling shoot'em up developed and published by UPL. It was only released in the arcades.

The game is set in some sci-fi/steampunk world. After worldwide economic depression, labour unions all over the world begin to strike and to riot. A mad scientist called "Gegeben von Funkeln" has formed a secret society called "Eisern Geist" to unify the unions in order to conquer the world. When the society starts its attack, it crushes all defenses. After 3 months, only a single bomber remains to to continue the attack on "Strahl", the steel fortress of Eisern Geist.

At the beginning of each stage, you can select one out of four different weapons for the three weapon systems of your ship (shot, missiles and bombs). Each system and each bomb has a certain weight, and your ship has a maximum weight it can carry. The number of bombs your ship will carry is determined by the remain weight left after installing the two other systems, and the weight of the type of bomb you chose. There are no power-ups to be found during a level, and bombs only get restocked if you go game over and continue. If you use a continue during a boss fight, you do not get bonus points after the fight. There is only a certain type of enemy which explodes and hits all in enemies in the explosion radius, if it gets destroyed.
Unsurprisingly, certain weapon configurations make a level easier or harder to pass.