Spoilers, a bit.
Two stars for the BFG 9000, keycards, hell zombies, Blazkowicz and imps (too overpowered though). That's were the Doom lore factor ends. I think most of the budget went to that CGI hell scene, which looked surprisingly okay. Everything else is pure garbage. Typical TV-MA waste of time. Stick to the actual game, which is still epic.