Units to attack the Creeper are created in Odin City. In order to power their weapons, energy must be gathered by Collectors, which are placed by the player. These Collectors require space in order to harvest energy and must be connected to the city's network. Should a Collector become isolated by the Creeper it becomes inactive and must be joined to the rest of the network in order to continue providing energy. The game's landscapes have different elevations, the Creeper can quickly spread across low-lying areas but must gather before rising to higher ground, like a liquid. Here the player can create choke-points to try and prevent the spread. Blaster units can attack the Creeper if they have line-of-sight contact but cannot attack higher elevations, while mortars can throw bombs into denser regions of Creeper and attack higher elevations.
In later missions the player is able to collect nodes to allow them to update their systems. IGN's editor named it their Indie Pick of the Week, stating «Creeper World may not be much to look at, but it's got it where it counts in the gameplay department.» Rock, Paper, Shotgun's Kieron Gillen stated that «Creeper World is the most apocalyptic game I've played in ages». Game developer Greg Costikyan stated that despite no element of the game being original «.they are combined in a novel fashion that makes the game worth checking out.» Big Download's reviewer called Creeper World's graphics «ridiculously simple» but added «.that works in its favor - their iconic nature makes for immediate identification.», allowing the player to see the whole battlefield as though it was a diagram.