Eschaton: Eschaton is built out of the regimen's own leftovers
Eschaton takes eight to twelve people to play, w/ 400 tennis balls so dead and bald they can’t even be used for service drills anymore, plus an open expanse equal to the area of four contiguous tennis courts, plus a head for data-retrieval and coldly logical cognition, along with at least 40 megabytes of available RAM and wide array of tennis paraphernalia.
Context
Before it's a nuclear-conflagration simulation it's a tennis-court occupation: the whole apparatus is scavenged from the academy's daily grind. Four contiguous courts get commandeered, the arsenal is 400 drill balls "so dead and bald they can’t even be used for service drills anymore," and the ordnance and targets are just "tennis paraphernalia." Eschaton is what the regimen's discards get reassembled into on the one sanctioned day off — the body's own worn-out equipment repurposed into a game the body still has to play with a racquet.