from which the player can install abilities, or extensions, to any of up to 3 characters. Any extension can be installed, depending on their prerequisites, but their rank (1 to 9) and attributes determine the cost for increasing levels. Although older players seem to have the advantage (having acquired more EP), younger players can install a wide assortment of extensions straight away, while older players will pay an increasingly larger amount of EP for smaller nominal advantages. Additionally, if a new player is willing to specialize, they can catch up quickly. Economy The in-game economy in Perpetuum is an open economy that is largely player-driven. Non-player character (NPC) merchants sell low level modules and ammo. The players themselves gather the necessary raw materials to manufacture a large portion of all of the robots, modules and ammunition in the game. NPC robots can be looted for items, kernels (to be sold or used for research, providing base knowledge to build items) and materials. The in-game currency is called NIC, an abbreviation for Nian Credit (the events of the game take place on the planet Nia). The amount of money or materials in the universe is not fixed and, as such, the economy operates under supply and demand. The game provides support for the trading of in-game resources, including graphs of item price history. Some players operate primarily as traders, buying, selling and transporting goods to earn profits. Others operate primarily as producers, purchasing components or raw materials and transforming them, sometimes on massive scales, into useful items such as modules, robots, ammunition, or various technologies wanted by players. Others still operate as miners, collecting and sometimes processing the raw materials used in manufacturing to sell on to others in bulk. Robots Robots in Perpetuum are organized into four general classes: Light robots, assault robots, mechs and heavy mechs. With the 3 alien factions, the game follows a rock-paper-scissors scheme, where each faction is weak to one faction, but strong to the other. Additionally, there is a fourth industrial faction, but they feature no significant offensive capabilities. Each robot has a different set of characteristics and can be fitted with different combinations of modules subject to their fitting requirements. Robots have a wide variety of characteristics, including (but not limited to) reactor size, CPU (robot's computer processing power), accumulator size and accumulator recharge rate (functionally, a battery for activating high powered systems),