GoKawiilBreakdown shows NetHack's Gnomish Mines use four-pass cellular automata
A technical write-up details how NetHack generates its Gnomish Mines levels: 40% of cells are randomly set as floor, then four passes of cellular automata rules (based on counting floor neighbors) reshape the grid into organic cave layouts, with a final step adding corridors to connect any isolated caves. The author breaks down each pass's rule set, noting that the first pass is applied without buffering while the remaining three use buffered updates across the whole grid.