This is the current teaser demo version of the FPS/RPG hybrid DOS game Strife by Rogue Entertainment.
Strife: Quest for the Sigil is a real mixture: the theme consists of sci-fi and fantasy and the genre is both FPS and RPG. The story has many details and twists. The player can make decisions which have an effect on the ending. Strife was also one of the last commercial games to use Doom Engine.