Innovation is a word that gets bandied about a lot but is rarely seen, especially in the realm of real-time strategy games. But every now and then, someone delivers a game that's completely unlike anything seen before. Perimeter is just such a game. This real-time strategy game from Russian developer 1C delivers a high-concept sci-fi setting, a load of innovative gameplay, and beautiful graphics. And though it falls short in a few areas, it's still a breath of fresh air in a genre in need of it.

The powerful perimeter shield in action; while it's raised, nothing can penetrate your defenses, but you won't be able to do much either.

To understand Perimeter, you have to understand the game's plot, which, we admit, is a bit bewildering. In the distant future, humanity is forced to travel to a new world through a series of different dimensions. In addition to battling rival factions trying to get to the end destination first, humanity also encounters the scourge, a strange, hostile life-form that inhabits the dimensional worlds and one whose shape is determined by human thought; it can be a dragon, a swarm of ants or other insects, and more. When humanity arrives in a new dimension in its "frame," which is like a huge floating city, it has to establish a base to charge up the dimensional gate and to power all of the defenses needed to protect the frame from attack. (These defenses include the perimeter, a powerful shield that can repulse any attack, but one that draws more power than can be generated, so it can only operate for limited periods of time.) And in order to construct power cores and other structures, the terrain must be terraformed into a smooth surface, which is why Perimeter could be considered a real-time terraforming strategy game; you dispatch droids to level mountains and hills and fill in canyons to create a flat surface. Part of the strategy is trying to figure out how to maximize the amount of land at your disposal in order to extend your chain of power cores to either reach an important objective first or encircle your opponent. It's a completely different dynamic from most real-time strategy games because land--for all intents and purposes--is the primary resource. In order to construct an effective base, you need to construct a network of energy cores (which also serve as the "fence posts" for the perimeter shield), research labs, factories, and stationary defenses, including lasers, rocket pods, howitzers, and subterranean guns that can knock out tunneling enemies. The more you build up, the more power you'll require, which means you have to build a larger base that's tougher to defend. On the flip side, you can also target the weak spot in an enemy's energy network to bring down seemingly insurmountable defenses.

One way to get around a defensive perimeter is to go underneath it. Here, a swarm of burrowers is causing havoc with the base on the surface.

Perimeter isn't just about base-building. When you go on offense, you have access to a powerful and unique unit system based on nanotechnology. There are three basic kinds of robotic units in the game: soldiers, officers, and technicians. Individually, these units aren't very powerful, but if you have the technology and the appropriate numbers of each unit, you can meld them together and transform them into something much more powerful, like a mobile rocket launcher, tank, or aircraft. You can even turn them into burrowers that can tunnel beneath an enemy base, disrupting the smooth surface and causing damage to the buildings. This reduces the need to build a gigantic army consisting of a half-dozen unit types, as you can just build one group that can transform to any need. And there's a traditional rock-paper-scissors relationship between the various units, so you have to constantly transform your units on the fly to adapt to enemy tactics.