Hey, so I'm playing through the GOG version of Doom 2 for the first time (having not played Doom 2 for a good few years), using gzdoom and the Brutal Doom mod. I just played The Suburbs level and seem to have stumbled across a secret level from there, called The Mansion. I'm a little surprised, as I haven't come across this one before and the [url=https://doom.fandom.com/wiki/MAP58:_The_Mansion_(PlayStation_Doom)]Doom 2 Wiki[/url] says that this level appeared in the Playstation and Saturn versions of Doom 2, but doesn't mention the PC version.

So, I am a little curious: was the PC version changed in some way for GOG, to include this secret level? Or, is it because I am using Brutal Doom? Did they add that in? (Although I wouldn't think Brutal Doom would be able to add an official level, without there being copyright issues)

(sorry, I don't know why the link is broken ... stupid GOG forum ...)

Can't comment on Brutal since I do not use this abomination but can comment on DOOM2. And it's very unlikely that base game had been modified.

Check your doom2.wad hash and size. If those have following values then game is unaltered.
md5: 25E1459CA71D321525F84628F45CA8CD
length: 14604584

Concerning 'commercial content to include in mods' issues, AFAIR, those 'new' levels are actually just old fan-made maps freely available at idgames archives for ages. As well, AFAIR, Brutal author is a jerk who mostly put together tons of the mods made by other people. So, there is nothing strange if some 'extras' suddenly appear.

P.S. See also: Hidden map(s) in Brutal Doom topic @ Doomworld.

Thanks for your reply. My WAD file has identical size and md5 sum to what you show. Ok, I wasn't aware the author is considered to be a jerk. I mean, I have seen 'composite mods' for other games, where they 'bundle' many mods together to make things easier for users, rather than people having to download and install dozens of individual smaller mods. I don't see anything wrong with that, as long as credit is given to the original authors. Although, if the Brutal Doom author has use other mods without acknowledgment, I would agree that is a bit low.

Are there any alternative mods you would recommend, for someone that wants to add cosmetic features, like more gore, gibs, blood spatters, but without any significant changes to the gameplay/level design? Ok, yes it says there that the Mansion level was added in Brutal Doom. That's interesting and it looks like it includes other secret levels from the Playstation version too. I mean, the level is interesting and fun to play, but I'm not sure such a significant change to the vanilla level progression was really what I was looking for.

Hmm ... the normal level exit of Gotcha! seems to have gone straight to PS16: Hell Gate, which interesting. Another console level I haven't played before. It seems Brutal Doom is certainly mixing some things up with the levels.

As they stated in the Doomwiki the console port replaced the wolfenstein secret leven with this mansion level.
I think Bethesda re-released the game with this to circumvent a ban in germany.
So no BrutalDoom does many things some goood some bad but it doesn't change the levels.
As it would make no sense since its a gameplay wad that should work with every map/mappack.

Well, he did something like that, plus difficult personalty, plus "celebrity decease" after his mix became popular among newcomers. I'm not a fun of such mods at all, as you can see... So, can citate only.
GZ-kiddies often recommend Smooth DOOM as a general eye-candy. AFAIR, this mod had been included in the Brutal, majority of it's code at least.
And there is Project Brutality which often is positioned as a healthy alternative to Brutal DOOM.
Try those two, may be one of them is what you want. If not -- try asking at Doomworld, ZDoom or GZDoom forums. GOG's version of DOOM II does not do so for sure. I assume that german version of the game might have some censorship when compared with the US release. Just downloaded latest setup_doom_ii_with_master_levels_1.9_(28044).exe, both Grosse and Wolfenstein are in place, and there are no traces of Mansion.

P.S. Took a look iside of brutalv21.pk3 and, yes, there is psxmaps.wad inside. So, the Brutal is a culprit.

Ok, thanks for the recommendations. I appreciate it!

Thanks for looking it up, never imagined it would do that.

I was surprised about that too. It didn't advertise anywhere about changing the level structure and I didn't see anything in the in-game settings. Although, to be fair, I thought the Mansion level was pretty good. Hell Gate was a bit crap though and Hell Bastion, which came after it before Nirvana, was so-so. Both are a bit dull imo for 'last third' Doom 2 levels.

Well, to my tastes whole last half of the original DOOM II is dull. Mostly large, mostly empty, mostly boring levels with low details on the landscape. And that has rather unpleasant explanation if you read "Masters of DOOM" book.
You, should probably try PlayStation DOOM TC for ZDoom-compatibles instead. I'd recommend Knee-deep in ZDoom and Antichrist DOOM as well. All of those make different approach to the common goal: revitalize old DOOM. I wouldn't recommend to use mentioned above episodes with gameplay mods like Brutal, though. They are feature-intensive already and something will definitely break in that case. And I wouldn't play Antichrist DOOM with (G)ZDoom at all since it will garble replaced sounds, use PrBOOM or Crispy instead.
May be Legacy of Suffering worth your attention too. GZDoom-only arena-shooter with replaced weaponry and lot's of eye-candies. But it's really good. Atmosphere is nervously active and fights are intensive.