I got a idea for a enemy that could appear on extremely rare occasions, maybe in Nightmare Mode only once every few dozens runs, maybe even more rare, a CRC Responder that was either tired of practices of CRC, or just thought that organization is hopeless and decided theyre better off alone, They would of course fight the infected, but also target Player CRC Responders, Their weaponry would be randomized, From the puny starter Model 10, up to a fully pimped out AR15.
Alteratevly, that enemy would spawn on every difficulty, And based on the difficulty it would be determined how geared and aggressive that enemy is.