Set in what one promotional flyer called "A future that might have been", where everything is run by steam but far more advanced technologically in some ways, the story begins with the evil General Sauron staging a military coup in the Motorhead Empire (read: World War II Germany). After a few years of war he has conquered nearly every neighboring country, save for one, the Republic of Silverhead which continues to resist.
Now both have developed their respective superweapons: the Silverhead have the "lightning bomb", a weapon that summon storms. The Motorhead have built some other, more secret weapon called the Lunanaught, eventually revealed to be a spaceship Sauron plans to launch into orbit to bombard Silverhead unchallenged. To prevent this, the Silverheads have launched a pair of prototype aircraft—a heavy fighter-cum-zeppelin, and a nimble ornithropter fighter with armor piercing missiles—armed with lightning bombs to prevent the completion of the Lunanaught. If they succeed, the war will be over...if they fail, Sauron will conquer the world. Guess who gets to pilot it...
Steel Empire, also known uninventively as Kotetsu Teikoku (鋼鉄帝国) in Japan and Empire of Steel in Europe, was released in the early 90s for the Genesis/Mega Drive and was later remade and remastered with some new graphics and sprites for the Game Boy Advance and later the Nintendo 3DS. In between missions, and at the beginning and end, the story is displayed in sepia-tone film screens and the whole thing is given the feel of a pulp serial from the forties or fifties. Basically it's Sky Captain and the World of Tomorrow in video game form, about twenty years early. Surprisingly, remakes aside, Steel Empire never had a sequel.
This game includes the following tropes:
- Airborne Aircraft Carrier: the primary means of warfare in the "Age of Steel" is by way of antigravity warships the size of aircraft carriers, launching fighters and bombers.
- Alternate History: it is, ostensibly, The Future. But a future where technology paradoxically both more advanced, in function, and less sophisticated in appearance. Spaceships powered by steam, Anti-Gravity ships with wooden hulls and Energy Weapons fitted on crude rocket-fighters, for example.
- Attack Drone: Averted; the Motorhead forces are manned bi-planes and jets. Despite the fact you kill thousands, they have more.
- Attack Its Weak Point: Many of the bosses are like this. One of them requires you to stay near the top of the screen so it lifts its cannon up- the cannon itself is invulnerable, but the cannon stands aren't.
- Battleship Raid: The third boss. Interestingly enough, you fight it in a very similar fashion to the battleship from R-Type
- Batman Can Breathe in Space: Your character (a steampunk plane/blimp) goes up to space to face the final boss. One must wonder how you can stay up for so long without the proper technology...
- Boss-Only Level: The final level takes place against the final boss and its multitude of forms.
- Chekhov's Gun: Remember how the intro said that your key to victory over the Motorheads would be your lightning bombs? Well, the Final Boss does a COMPLETELY UNAVOIDABLE attack once it's low on health and will keep on spamming it with increasing intensity... but wait! Your Lightning Bombs give you temporary invulnerability while damaging him...
- Well, it's not COMPLETELY unavoidable — the asteroids floating through the screen on the Genesis give you temporary shelter from the walls of fire, while your increased firepower and helper drones lets you continue to attack. Of course, if you died on on this level, things become much dicier, since you lose your upgrade firepower and helper drones.
- Continuing is Painful: While dying doesn't set you back to a checkpoint, it does remove your outrigger planes, and if you use a continue, you just get sent back to the start of the half of the level you game-overed in (keeping all the experience item counters you collected). The Game Boy Advance remake, however, raises this up a bit by also dropping your firepower back down to level 1 on death while resetting your lightning bomb counter.
- Cool Plane: The ornithopter. The Zeppelin might as well be one, given it's maneuverability and firepower.
- Corridor Cubbyhole Run: The Final Boss has an attack like this, where it shoots out near-unavoidable waves of fire. You have to hide directly behind the asteroids to avoid it.
- Deadly Walls: Touching walls makes you lose health.
- Death Course: The second level, where you ship has to outfly a collapsing cavern while avoiding the terrain on the way.
- Doomed Hometown: The carrier ship that you start out in (and return to refuel for the first few levels), the Rheinhalt, gets taken down by one of the Motorheads' giant airships. You get your revenge by blowing up two of them!
- The Empire: the Motorhead Empire, a brutal imperialistic state which is out to conquer its neighbors. Never outright stated, but basically implied to be coeval with WWII Germany.
- The Federation: your side, the Republic of Silverhead. Basically the British Empire, if the comparison between the two states holds.
- Marathon Boss: The Final Boss has several phases, the very last section of which has no less than 5 (where it changes its attack pattern per phase). Taken even further in the 3DS remake, which adds even more phases to it.
- Military Mashup Machine: a zeppelin-fighter-bomber, or a zeppelin-airship-submarine, or a winged ornithroper fighter, among others.
- Mook Maker: The aircraft that drops tanks in stage 1, Tank/hovercraft bunkers, the giant airship boss(es), etc.
- Names to Run Away from Really Fast: Gee I wonder if a guy named Sauron is evil?
- Nintendo Hard
- No-Damage Run: Beating a level without taking any damage (very difficult) gives you a large score bonus.
- Pintsized Powerhouse: The Final Boss is the smallest boss in the game compared to the behemoths you've faced, and it has much more health and firepower than any of them.
- President Evil: General Sauron, ruler of the Motorheads.
- Raygun Gothic: This game, full stop.
- Recurring Boss: Lots. Many of the minibosses return later as minibosses, the first boss (the train) appears again as the third-to-last boss, and the ocean stage's miniboss appears as the second-to-last boss.
- Red Shirt Army: The Motorheads seem to succeed in their conquests because they have 100 to 1 odds, since they go down like Thai hookers when you show up.
- Rocks Fall, Everyone Dies: One part of the second stage has loads of boulders falling on your character, and it gets very irritating...
- Schizo Tech: The Age of Steel includes steam powered space ships, flying vessels, guided Buzz Bomb-like missiles, and energy weapons. Otherwise it appears to be little changed from the early twentieth century.
- Shout-Out: The third boss (especially its weak point) is more than a passing resemblance to the airborne battleship from R-Type.
- Smart Bomb: the Silverheads' new weapon, the Lightning Bomb, is a missile that summons targeted energy blasts from space... somehow.
- The Swarm: the Motorhead fleet's primary method of attack. They send fighters and airships by the thousands to swarm their enemies.
- Video Game Remake: The 3DS version, which has several of the bosses, levels, and enemies modified.
- Zeppelins from Another World: by the bus load; the primary means of warfare and travel in the Age of Steel.