Depth Dwellers

Depth Dwellers is a first-person shooter released in 1994 by TriSoft for MS-DOS. The game was designed to work with 3D glasses. It was also included with the Woobo Electronics CyberBoy unit. Being released in June for the first time as a shareware product, it predated Raven Software's Heretic by six months in being possibly the first game to feature a pseudo-3D engine that allowed players to look up and down freely. The game also permitted ducking and jumping, which were still uncommon abilities in most first-person video games of that era.