geoDefense Swarm follows the well received original geoDefense. The same style is included, but instead of fixed path tower defense it's now open field. Every level provides a unique challenge on a grid composed of hexagon shapes. Now the paths aren't given to you, but rather you have to build the mazes with towers.
In open field tower defense you place towers to set up mazes that the creeps have to go through. Each tower costs money, and you have a pre determined amount to start, and earn more for each enemy you destroy. Your goal is to defend your base from a certain number of waves of creeps. A bunch of new features are included that weren't seen in the original.