Many real-time strategy games center on massive battles between different types of tanks. Metal Fatigue takes this convention to the next level by focusing on "combots," giant robots reminiscent of those in various Japanese animated cartoon series. Metal Fatigue's concept is innovative both in its modular unit design and in its multilevel battlefields that take place in orbit, on the surface, and underground all at once; but the game's unbalanced units, as well as a few interface problems, cut it short of its potential.

The game's story is similar to what you might expect from giant robot anime such as Macross and Gundam. In Metal Fatigue, three corporate factions, which coexist in an uneasy alliance, have discovered alien technology in the far-off Hedoth system. In an initial skirmish over the discovery, three brothers - Diego, Stephan, and the treacherous Jonas - find their loyalties split among separate factions, and soon, open war breaks out. A ten-mission campaign is devoted to telling the story of each of the three "CorpoNations": the balanced RimTech, the aggressive MilAgro, and the high-tech, stealthy Neuropa.

Each CorpoNation has its own combot technologies, but during the course of a mission, it's possible to retrieve parts abandoned on the battlefield and research them for your own faction's use. What makes this possible is the modular construction of the combots themselves, as each is constructed from four components - torso, legs, and right and left arms. While the modular design somewhat reduces the visual distinctiveness of each side, it does make it fairly easy to eyeball the composition of your opponents. In fact, much of the game's strategic interest lies in adjusting your combot production to best oppose the combot designs you're facing. The array of available melee and ranged weapons can deal out either energy or kinetic damage, and the various defenses can defend against either type. In addition, torso and leg designs can provide extra armor or special abilities such as cloaking, increased hand-to-hand damage, and jump jets.

In stark contrast with the complex modularity of combot production, there are only four conventional offensive units: a tank, a mobile surface-to-air missile launcher, a modest artillery piece, and a special combot-debilitating spell unit. The conventional units are rather simple and are functionally equivalent for the three sides. The primary use for conventional ground units is to go into the subterranean tunnels that are much too small and unstable for the giant combots. Yet, as support units for your main combot cavalry, they are often little more than expensive targets. A speedy melee-equipped combot can quickly turn a tank battalion into a gutted mass of metal. The primary base defenses also seem underpowered, considering their cost and build time, though the walls and gun emplacement have the atypical, yet convenient advantage of being mobile. Metal Fatigue doesn't aspire in any apparent way toward a rock-paper-scissors unit balance, and, in practice, it rewards you simply for throwing as many multipurpose combots at a target as possible.

Furthermore, the mix of very large and very small units exacerbates the game's pathfinding issues, the chronic weak point for real-time strategy games. The game's 3D structures and units alternately seem capable of packing impossibly tightly together one minute; while in the next minute, they seem to get stuck on thin air. Though you might think that a militaristic bunch like the MilAgro could march lockstep in their sleep, its units refuse to follow movement orders sensibly with disproportionate frequency. The problem is compounded when a squad of large combots tries to walk in a tight-box formation, the only one available. Too often, a valuable combot will get stuck behind just a few tanks and will twist and turn uselessly, trying to find a way out. When a combot is under heavy fire in tight terrain, supporting tanks will without a doubt prove to be a deadly hindrance.