After update to version 2.1 Its much better, but i think enemies should not shoot at player when they are out of render at least those hitscanners. Zombiemans.
Also a good addition would be possibility to run this with original wads. If you also could do something with invisible doors, maybe indicate them with a symbol that will popup at different layer than door, when a player is close? (Something simple, triangle maybe?)
This can turn to another yet very different port of doom. It needs polishing but it is possible.