If you want to start a Bloody Nightmare NG+ directly without going through a new game, do this

- start a new DOTM
- bring the console and type these commands:

skill 3

impulse 223

impulse 224

changelevel map1

You'll know that you are in NG+ as you get the Bloody Shotgun immediately on map1

And here's the full list of impulse (some may need sv_cheats 1):

impulse 1-8 changes weapons
impulse 255 also changes weapons
impulse 9 gives all items EXCEPT runes
impulse 99 gives all items EXCEPT keys and runes
impulse 10 cycles weapons
impulse 11 uses ServerflagsCommand
impulse 12 cycles weapons backwards
impulse 100 temporarily undoes effects of upgrades
impulse 101 gives rune 1
impulse 102 gives rune 2
impulse 103 gives rune 3
impulse 104 gives rune 4
impulse 105 gives all runes
impulse 111 gives next health upgrade
impulse 112 gives next shell upgrade
impulse 113 gives next nail upgrade
impulse 114 gives next rocket upgrade
impulse 115 gives next cell upgrade
impulse 116 toggles secret hunter cheat
impulse 117 toggles exit hunter cheat
impulse 118 gives super axe
impulse 119 draws alive enemies
impulse 121 toggles buddha mode (health won't drop below 0)
impulse 122 toggles infinite ammo
impulse 220 enables a dimlight effect
impulse 222 reloads the map without removing progression
impulse 223 toggles 'bloody nightmare' difficulty
impulse 224 toggles Newgame+ flag
impulse 227 toggles shotgun upgrade
impulse 228 toggles super shotgun upgrade
impulse 255 gives quad damage

Very helpful, thanks for this

What do impulse 116 and 119 exactly do?

- impulse 116 draws blue dots in the whole map locating secrets. Dots get bigger as you get closer

- impulse 119 draws a red wireframe rectangle across living enemies in the map, allowing to locate monsters you have not killed. It requires sv_cheats 1 to work.

Thank you! I got a lot of missing enemies in my DotM playthrough, but I think they most likely were stuck zombie. So this is helpful

Yes but only at a certain distance (otherwise it would be too cluttered).

I was hoping there would be a way to get the bloody upgrades for the shotguns in the other Episodes, but it looks like they're only supported in Dawn of the Machine. I'm guess modding is needed to add them to the other episodes.

Out of curiosity, how did you get this list? Is the source available? Or did you try one by one?

I decompiled progs.dat with fteqcc and searched for impulse. The list I pasted is actually the help text in the code and will display if you have developer 1 and type an invalid impulse command (such as impulse 254). Interestingly, impulse 219 exist in the code but was undocumented (I added it myself to the list).