Acid Reflux is a map set for Boom-compatible source ports where you delve through acid-filled sewers, factories, and... subway stations? It should take you around 30 minutes to finish the whole set, and the maps get progressively longer and tougher as you go on. The map contains custom weapons, namely an auto rifle which replaces the pistol, and an upgraded chaingun. Plasma marines replace the wimpy Former Humans, with sprites done by @Tango.