Creeper World is a pausable real-time single-player strategy game with tower defense elements. The goal of Creeper World is to build generators and guide power to a warp gate. Once the warp gate is fully powered, the player's city-ship may leave the planet and continue its journey. Hindering this goal is the titular creeper, a mysterious entity which behaves like a fluid, flowing down hills and through valleys. As the creeper accumulates and spreads, the player must build weapons to keep the creeper at bay long enough to gather vital power.
Each level starts the player with only their main 'base' (Odin City), and a small amount of resources. Levels also contain one or more 'totems' that must be activated to power the warp gate; powering all totems at once counts as a success, with the score for a level starting at 10,000 and slowly decreasing over time. Levels also have creeper emitters which begin pumping the creeper fluid onto the map shortly after the game begins. Levels are not flat, but have hills, valleys, depressions and other vertical features; these will cause the creeper to spread in certain directions or areas but are generally below the maximum level the creeper can reach. Maps rarely have permanently safe areas. Some levels (mostly those in the story mode) may also contain other features, such as temporary barriers, 'nano schematics' (which unlock abilities) or upgrade nodes.
The player can choose from a number of different types of items to place on the map. Items can only be constructed and powered if they are connected to the resource network, although weapons can be moved freely once built.
- Collectors & Relays: Collectors are short-range network nodes, which also provide a small boost to energy production. Relays have no boost and have the same connection distance to other note types, but connections between relays can be much longer.
- Blasters & Mortars: Short-to-medium range weapons that attack the creeper directly. Blasters fire quickly but only destroy one layer at a time; mortars fire slowly but further and can destroy much larger amounts. If all nearby creeper is destroyed, a single blaster is able to 'cap' a creeper emitter indefinitely. These cannot be 'chained' - they must be connected to other nodes.
- Drones & SAMs: Once ammunitionalised, drones can be targeted to any point on the map, and will proceed to fly there and drop bombs that can potentially destroy very large amounts of creeper. SAMs are entirely passive weapons that will automatically destroy creeper 'spores' (meteor-like balls of creeper targeted towards player structures that otherwise explode on impact, only present on some levels) and are the only weapon capable of doing so. Drones are the only weapon that cannot be moved after construction and the only weapon that does not fire automatically.
- Speed/Energy upgrades & Reactors: Extra nodes that provide a passive boost to some part of the network - the former increase the speed that particles travel or the total amount of energy that can be stored at once, and reactors provide the same extra energy as a collector in a smaller area (at the cost of being much more expensive to build).
Weapons that are touched by creeper are slowly damaged and will regenerate over time, but all other nodes will be immediately destroyed, potentially cutting off sections of the network. Particles will always take the shortest route as long as there is a path, but nodes not connected to Odin City cannot be resupplied with ammunition or provide any benefit.
The creeper fluid is the only obstacle on the map, but total destruction is not the objective and often unnecessary. Players must balance energy production with defense and offense against the creeper - if more energy is being used (through ammunition supply, building nodes or powering totems) than produced then energy will be transferred at a reduced rate, which may cause a weapon to fire more slowly, causing the creeper to get closer, which might cause a relay to be destroyed, which might cut off a network section and reduce energy production even further... However, being too cautious and expanding too slowly can allow the creeper to fill up the lower map sections or overwhelm barriers and become ever harder to push back.
The campaign mode takes place over twenty preset levels, increasing in difficulty as the player progresses (with the earliest levels functioning as a tutorial as items are introduced). Levels may include other objects such as rescue pods or 'mysterious artifacts' that are sometimes necessary to proceed, but generally have the same requirements of powering all the totems to active the warp gate. Each level represents one of the thousands of planets that have been overrun by creeper, with the plot and backstory developed between them (and occasionally within) and the player changing from leader of an evacuation to attacking the creeper head-on.
Other Game Modes
'Conquest' consists of another 25 levels, available in sets of five, with no plot or special objectives.
'Special Ops' contains ten themed maps (unlocked by progressing through Conquest), with terrain resembling the Earth, a skull and cross-bones, or other recognizably non-random patterns.
'Chronom' takes a date chosen by the player and creates a random map (that will always be the same for a given date) of varying difficulty.
Finally, custom maps can be imported and played.