A strange little side quest
The rules may be simple on screen, but the backstory around Rooftop Battles is anything but tiny. Doom changed game design and distribution in 1993 by separating its engine from content and spreading widely through shareware. The same trail leads to another fact: Pac-Man went on sale in 1980, and its creator Toru Iwatani famously linked the character's shape to a pizza with a slice missing. The details change, but the appeal of learning a system and trying again is remarkably persistent.