Creeper World, by Knuckle Cracker, despite the off-putting name, is a really interesting iteration of the standard Tower Defense genre. In most such games, you must protect a path from a given number and type of enemies by planting a given number and type of weapons in various locations along the route. Most tower defense games are pretty much the same.

Creeper World is different in many refreshing ways. First, the entire premise is not the same as the standard, which is outlined above. Instead, you have command of Odin City, which allows you to build your offensive units. It is these units that you must build that will fight the enemy. You do this by planting Collectors, each of which provides a small amount of energy to the city. Collectors must be given a certain amount of space to do their energy collection, which it then transmits back to Odin City.

If for any reason a connection to the city is broken, the Collector goes offline and can't provide energy. It isn't destroyed, which means that it can be activated later by reconnecting it to the network. Collector deployment is critical to playing Creeper World, as your weapons must be powered by the network.

Second, the enemy you face is the same enemy every time: an amorphous blob called The Creeper. The Creeper spreads in all directions, threatening your holdings, rather than advancing along a single path. This makes it much more difficult to fight, as you must decide where exactly you want your choke points to be. And your weapon locations depend on their availability to the network. The Creeper can't be destroyed, only held at bay.

Third, elevation and terrain are important considerations in the battle. The Creeper can be geographically contained by steep walls, but you have no control over that. Instead, you must decide where best to place your weapons so they have either line of sight targeting of The Creeper, or can lob bombs into deeper areas of The Creeper, which holds it for a short duration.

Fourth, your economy isn't measured in money, but in power consumption. There are tiny interface areas that show you how much power you're collecting, how much you're using, and if there is a deficit. All weapons use a certain amount of energy, and some more than others. If you start running into the red, you'll need to destroy some power-hungry units.

The level ends when you can connect the network to three separate totems; when these totems are brought on-line, they create a warp gate that allows Odin City to escape the planet and The Creeper. You then move on to the next planet, whose terrain and topology creates a whole new playing field to figure out.

Creeper World features ridiculously simple graphics, but that works in its favor -- their iconic nature makes for immediate identification, and taking a step back from the screen displays the whole battleground very nearly as an informative diagram. The challenge of each level is much more sophisticated than the average Tower Defense game, and there is no one way to finish each one. This game is a must-have.