This is intended to bring some of the action from the popular Doom series to the Fallout world via the VRGC (Virtual Reality Gaming Console). As such, this basically strips you of all items going in and coming out, although some of the possible rewards might involve learning how to make the equipment you use in the Fallout world, or you might accidentally figure out how to open an actual hellgate. Or maybe I'm overthinking this.
At any rate, Doomed adds new weapons, apparel, aid items, msic items, and ammo types, as well as providing various worldspaces, interior cells, and crafting opportunities. It has at least one primary questline, as well as side quests and unmarked quests. Initial implementation of monster types will use existing models equipped with monster-use-only weaponry and equipment - for example, Imp fireballs would be based on an NPC weapon that throws fireballs similarly to the incinerator but without an arc.
Doomed adds the following content: