Pop-Up, Oklahoma is a small town community that was formed during and endured the Chimera occupation, the settlement got its name from the fact that its citizens lived underground and it is located near the abandoned Kildare. By 1954, Pop-Up's settlers survived from the Chimera's genocidal onslaught by living underground, with homes being at least half a mile apart from each other, which meant that if Death Squads stumbled across one of the homes, the others had a chance of surviving. Residents usually kept to themselves apart from a loosely knit co-op-style government that primarily focused on providing health care and education and a fifty-foot-wide circle of wooden stakes, each topped with a Chimeran skull, facing towards a bonfire in the middle where the local families met. Pop-Up was known by the surrounding Oklahoma communities as a place with a large volunteer miltia, which could field as many as thirty soldiers, making them valuable allies.
In January 1954, Pop-Up was visited by six New American Republic regulators who wanted the community to be part of the ever growing American Empire which was ruled by Judge George Ramsey. The Pop-Up settlers were upset by the way the 'invitation' sounded like an order and declined when settler Harvey shot the N.A.R's messenger and his fellow Pop-Up citizens killed four of the remaining five regulators. A few days later on the 10th, neighbouring community Haven and remnants of the United States Army under the command of Captain Marvin Kawecki visited and succesfully enrolled the citizens of Pop-Up into an alliance against the N.A.R's settlement Tunnel-Through. Pop-Up settlers did fight in the First Battle for Tunnel-Through which turned out to be a failure with an unknown amount of Pop-Up casualties.
Pop-Up's citizens are masters of camoflague and various field craft due to that the settlement resided in mostly flat and generally open terrain where the only cover was skeletal trees. The locales were good hunters as well, shown by the wool clothing, bucksin and furs that they were dressed in, however, they weren't good at personal hygiene, due to the lack of running water in their underground barrows.