I don't think my feedback here will be 100% fair because I cannot figure out what to do after you enter the negative mode. I was trying to collect weapons and the letter but the game always drop the frame rate to an unplayable level after a short while and I'm out of ideas.
But from what I experienced so far, the atmosphere is incredible and I'm always a sucker for meta-games so the error message gave me chills in a good way. I've never played the original doom but I still love the aesthetics. I do think it would be a great "explore and figure out the story" type of game and be well received by many, but to me there is probably a too big of a lack of hints. Other than that no complaint. I'd totally play again if this game gets expanded to full.