Imagine if a comet broke up before impacting our planet, and the pieces slammed into population centers before covering themselves with a seemingly impenetrable force field. Now imagine that it's your job to take a small number of units into these areas, which are being called "anomalies," to figure out what the hell is going on. And then you discover that the environment inside these anomalies is much more hostile than you could have dreamed.

It's a wonderful setting, one that does a great job of turning the tower defense genre on its head. In Anomaly: Warzone Earth, we're the invading force, trying to regain control of a situation we don't understand. The sense of tension and fear in the early missions is palpable, making it easy to forget that the game we're playing has us looking at tiny units from a great height. An injection of humanity is not common in this genre, but such is the way of pleasant surprises.

Control, explore, destroy

Your job is to escort your units through the city streets, keeping them safe from attack while moving toward a final goal. At the start of each mission, you plan your route with a tactical screen that shows the layout of the city and gives you a chance to plan your course around—or through—the enemies. You can jump into this screen at any time to change your plan of attack.

The conditions on the ground can change any moment, so you'll have to think in terms of both the individual battles and your overall movement. It sounds like a lot to get your head around, but the game does a good job of introducing you to the core mechanics in the first few missions.

You earn money by destroying the enemy defenses and by picking up material from the battlefield, and you can use it to buy more units or upgrade those already on the field via the tactical map. You can also change the order of your units, and as you unlock new units to use in the heat of battle, the order they roll in can make or break your attack. There are only two difficulties right now, casual and hardcore, and the difference between them is rather punishing. We're hoping for a middle ground before the game launches.

It's not all high-level tactics, though. During the mission, you'll control a commander on the field, and your job is to support your vehicles by using your special abilities. These include a repair function that keeps everyone in working order and a smoke screen that obscures your position so you can attack the enemy unmolested. You'll unlock more as the game goes on, and you'll have to think on your feet in order to use them in the most effective way while finding a smart course through the level. It's a clever combination of long-term strategy and action-oriented gameplay.

This game is a very pleasant surprise, created by a small team and pitched to us during the Game Developers Conference. A few days later, we were sent a preview build and fell in love. This looks like other games in the tower defense genre, but it plays like nothing else. The game is coming for the PC, Mac, iPhone, and iPad, and is one to watch. We're told that 11 bit Studios is looking at a sequel where you actively play against another player, creating a sort of competitive, multiplayer tower defense game.

You have the ability to speed up gameplay, but I wouldn't use it if I were you: you can find yourself in a situation over your head before you know it. The reversal of the tower defense idea is a good gimmick, but the execution is what makes this such a high-quality game. We'll let you know when it's close to launch.