As of 0.18, monster is part of the crawl source distribution: https://github.com/crawl/crawl/ in directory crawl-ref/source/util/monster/ To build monster for 0.17 (likewise 0.9 through 0.16): git checkout dcss017 # On the first build: git clone -b stone_soup-0.17 https://github.com/crawl/crawl/ crawl-ref # Subsequent builds: # cd crawl-ref && git checkout stone_soup-0.17 && cd .. make