A singular map made of of all the original Quake levels, allowing for a single contiguous play-through. Play from beginning to end without any load screens. Also featuring improved geometry and fixed bugs.
Extract quakemash.bsp into the /id1/maps/ directory (create if necessary) in your Quake directory.
E1M8 is a secret level with low gravity. For this to work requires a mod that properly supports trigger_setgravity such as dumptruckDS' progs_dump mod.
Set your skill before loading the map, e.g.:
./darkplaces +skill 5 +map quakemash