The four time periods are "Berlin, 1944" (tanks, troops delivered by trucks and railway trains, zeppelins, air strikes, commandos trying to hook lines to the Walker to climb up and mount bombs on its back); "Los Angeles, 2019", a post-apocalyptic wasteland very close to the future sections of Terminator (troops with laser weapons, robot tanks and aircraft); "The Middle East, Tonight" (The Gulf War; the enemy appears to be American forces and will bomb you with A-10 Warthogs) and "The Great War, 2420" (futuristic enemies in a wrecked Crystal Spires and Togas city). The last two could only be reached on the games' unforgivingly difficult "Arcade" mode. There was also a pre-release demo in "Constantinople, 1918" where British/French/Italian troops face you with cavalry, rifles and horse-drawn artillery.
The game is particularly notable for its control scheme - the joystick (or keyboard) is used to steer the Walker left and right (forward and backward respectively), while the mouse (or a second joystick) controls the aim and the guns (common now, but it was unusual then) and being rather graphically violent for a mechanised warfare shooter with '90s graphics: much like in DMA's earlier hit, Lemmings, deaths are rather gory, despite the tiny size of enemy soldiers cut down by the Walker's huge twin machine cannons. Everything explodes, often with screams of pain echoing in the background and there is almost no end to enemy troops. Also, in a minor note, the game is unusual in moving across the screen from right to left, while virtually all other side-scrollers go left to right.
As for why the Walker is stomping through time, that involves temporal warfare: It's the early 25th century and after three decades, warring nations Myarn and Endalion have found a new dimension to their conflict: due to the planet's "shifting polarity", time travel has become possible. Endalion, the first to realize the potential, begins to literally erase entire enemy units out of existence with its knowledge of past events. Myarn, faced with annihilation, creates the AG-9 Walker, a self-contained, energy-efficient unit, capable of traversing any terrain and powerfully armored. However, an Endalion strike destroys the Walker factory, and only one unit returns from its mission, heavily damaged. This surviving Walker is now tasked to strike at four key Endalion positions, each located in a different time and place, as Myarn's last hope...
Contains examples of the following tropes:
- After the End — The second stage, Los Angeles 2019, is happening during the "Judgement Day", as it was later called by its survivors. If that sounds a lot like the backstory of Terminator, then the appearance of troops with laser rifles and robots looking just like the "Hunter-Killer Tanks" will also be familiar.
- All There in the Manual — The game manual contains the entire backstory, along with many detailed sketches of the Walker. The sketches differ in details from each other and from the game sprite—they're explained as rough engineering sketches found in a capsule and drawings made by an eyewitness. Notably, the design notes state that the emergency escape mechanism likely never made it to production units, which is contradicted by the ending.
- Attack Its Weakpoint — Goes both ways: the boss enemies can only be damaged by shooting specific parts of their armor, often in correct order, while enemy troops will often try to attach a bomb to the Walker's only weak spot, its protruding heat sink.
- Bottomless Magazines — It's a design point for the Walker to be self-contained, though the details of how it keeps its machine guns supplied with ammo is left unexplained.
- Checkpoint — At the midpoint of each stage. Also has the benefit of regenerating the player's shields.
- Chicken Walker — The machine controlled by the player uses this configuration. It even has very bird-like "feet" and its head resembles a bird skull.
- Critical Existence Failure — The player's machine works perfectly... until enemy attacks tear through the entire shield and the entire armor, at which point the Walker explodes violently, leaving only its feet behind.
- Crosshair Aware — Some areas of the Berlin level are initially empty but for you and a flashing crosshair on the ground, which warns you that the Luftwaffe are about to bomb the whole area. In the Los Angeles level, enemy suicide bombers will run from your crosshair if targeted.
- Deflector Shields — The Walker is equipped with these. With typical Nintendo Hard stinginess, they only regenerate at the stage's midpoint and between levels.
- Earn Your Happy Ending — Subverted. The player needs to choose the arcade mode and beat all four levels to finally see the ending, but the fate of the protagonist remains unclear.
- Easy-Mode Mockery — Beating the stage two boss on the easier difficulty results in a game over screen showing a destroyed Walker, captioned "Now try arcade mode!".
- Featureless Protagonist — Played with: nothing is known about the Walker pilot, other than the fact that's he's definitely male. However, those lucky enough to have a machine with more than a megabyte of RAM could hear him frequently taunting his enemies, so he's not a Heroic Mime and he does have some personality.
- Gainax Ending — The ending cutscene shows the Walker's head detaching itself from the main body and powering a "warp drive" in an attempt to escape a thermonuclear bomb, as the final boss explodes. The animation presented from the cockpit view shows the gigantic explosion coming closer and closer while the head flies through the ruined landscape. The cutscene ends with a flash just as the explosion reaches the escape pod, leaving the pilot's survival ambiguous.
- Gorn — The intro cutscene has a soldier getting gunned down in a fountain of blood. It gets worse, despite the enemy soldiers being composed out of only handful of pixels, thanks to detailed animations and the sheer amount of Mooks to gun down. (This was the same studio who made Lemmings; they could pack a lot of graphic violence into 8x8 pixels.) Bonus points for allowing the player to simply stomp the enemy soldiers, leaving suggestive pools of red behind.
- Humongous Mecha
- It's Up to You — The Walker is the last surviving machine of its type, and you won't see anything else that isn't hostile.
- Just Plane Wrong — The American fighters attacking the Walker in Berlin level are not only able to drop an enormous bomb payload, far too large for this type of plane, but even several paratroopers in one flight.
- Qurac — The "Middle East" stage.
- Next Sunday A.D. — The game doesn't come out and say that the Middle East level is Iraq during Operation Desert Storm, but sets the time as "Tonight".
- Nintendo Hard — The Arcade difficulty. For starters, you now fight two of each stage one and stage two boss... at once.
- Scenery Gorn — WWII-era Berlin and Gulf War-era "somewhere in the Middle East" have been reduced to rubble by warfare, 2019 LA is a post-apocalyptic wreck, and 2420 has a background of huge buildings of a Crystal Spires and Togas future, smashed up and pocked with damage.
- Schizo Tech —
- The first stage nominally takes place in Berlin in 1944, and the enemy units have apparently contemporary (or even somewhat anachronistic) weaponry that makes sense (besides the limitless amount of armour and men they field against you) until you reach the the stage's two bosses, a gigantic, armoured zeppelin, and a well-defended rocket launch pad.
- The future enemies are armed with laser weapons in 2019 and God knows what in 2420, which makes it odd that the Walker, from further ahead than either of them, is armed with old-fashioned machine-guns.
- Timey-Wimey Ball — Both sides of the conflict use Time Travel to wipe each other from history. However, the final result is left rather ambiguous and how even one Walker unit could survive despite its factory being destroyed beforehand is not explained.
- Video Game Cruelty Potential — When the player does enough damage to an enemy helicopter, he may choose to stop firing and watch the pilot desperately struggle with his crippled machine. Eventually, the helicopter will come down and explode, sending the screaming pilot in the air.
- Walking Tank
- Zeppelins from Another World — A stage one recurring enemy is a zeppelin so large, we only ever see a part of its bottom, apparently armoured well enough to withstand continuous fire from the Walker's guns. It does eventually go out with a huge bang.