Open rebellion is designed to be adaptable to a wide range of settings. The setting presented on this site should be understood as but one example. OpReb would be a suitable ground combat system for anything from WWII, all the way through space opera.
We are currently using a plausible Sci-Fi setting, where the tech level is more or less achievable with today’s scientific and technological capabilities. With a few noteworthy exceptions, the tech level is set at what can be achieved now. Some technology is represented in a smaller form than its current version, but the scientific principles are solid and executable.
Some of the exceptions are the mechanized robotic battle suits, or mechs, which initially evolved from mechanized, hazardous environment suits, used in difficult chemical and radiological cleanup operations. They were later used for extraterrestrial exploration, and it was really, only a matter of time before someone loaded them up with guns, missiles and ceramic composite armor and sent them to war.
We are also postulating interstellar travel via generation ships, not quite achievable in today’s technology, but nevertheless, a plausible method for deep space exploration.