- Install Chocolate Doom by following the instructions on the Chocolate Doom download page
- Download resource WAD files dm_iog.wad, iog_assets.wad and freedoom2.wad
- Run Chocolate Doom:
chocolate-doom -iwad path/to/freedoom2.wad -merge path/to/dm_iog.wad path/to/iog_assets.wad -altdeath -warp 30 -dehlump