The player in Perpetuum is loosely represented as the remote-control driver of a robot. Robots are generally classified according to their size first and nationality second, although in the case of Niani (industrial) robots, this convention is abandoned for the simple name “industrial.”

It is worth noting that although nothing larger than a heavy mech currently exists as of January 2012, the game appears to support a framework which would allow for the existence of a larger robot. Weapons, for example, currently only reach medium size - no “large” size weapon exists. Similarly, no mech of any size requires more than Advanced Robotics 4.