The maps are standard BSP and BSP2 format, and can be loaded by any engine or tool that supports those formats. 

Don't decompile things you don't have the source files for. 

"But I want to open it in an editor!

The author doesn't want you to. Cry about it! 

Probably not bsp2 though. 

QuArK can *display* BSPs, but it can't edit their geometry. 

I thought you could use winqbsp to decompile them into a map. The issue is, it will generate so much microbrushes it will look like a complete mesh.

I did a few bsp files with it once and used quark to "mirror" them.
A lot of time, but succeeded. 

Decompiling the work of professional level designers to see how they made it is a great way for amateurs to learn. Without such practices communities like this would likely have died out years ago. Indeed, I imagine Carmack and Romero themselves probably wouldn't think twice about it, and had they not rooted around in other people's code many years ago the FPS may never have been invented.

Redistributing other people's work without their consent is another matter, but OP didn't claim they want to do that, so you should probably climb down off that high-horse. 

Without such practices communities like this would likely have died out years ago.

Quake mapping carried on just fine for however many years it took before distributing .map files became norm (which is still a relatively recent development).

I realise it's extra helpful to provide your map sources, which is why I've encouraged this practice in every jam/speedmap I ran.

But my point still stands: if somebody didn't share the source files, it probably was for a reason. Decompiling is not the right way of getting around it. 

if somebody didn't share the source files, it probably was for a reason.

In this case that reason will be "Bethesda". There is a legal argument to be made here which is separate to the moral argument, and neither supercedes the other.

Either way, my response to you was largely to reassure OP who is a brand new member of the forum and doesn't need to be greeted with snarkiness. 

It's bad practice and should not be normalized - full stop. 

It's already normal, and that should continue- exclamation mark! 

You shall not draw my castle.
It's owned by the architect.
:P 

Wolf3D was closed source, but when id Software saw all the user content created from reverse-engineering their files, they decided to create file formats that were more open.

Quake's BSP format is hard to decompile not because id Software wanted to stop people from modifying their files, but because its optimizations results in a substantial loss of the original data. 

Quake's BSP format is hard to decompile not because id Software wanted to stop people from modifying their files, but because its optimizations results in a substantial loss of the original data.

This is related to the map creators not sharing .map files how?

And I didn't just mean maps, but also decompiling progs, which people seem to be OK with nowadays as well (newsflash: it isn't). 

This is related to the map creators not sharing .map files how?

It's not related to the sharing (or not) of .map files, that's a tangential matter that only you have mentioned.

It is related to the practice of decompiling BSP's (the topic of this thread) because in conjunction with the well known fact that Quake's creators are a-okay with people butchering and reverse engineering their product it demonstrates that there is a longstanding precedent for such practices. 

And I didn't just mean maps, but also decompiling progs, which people seem to be OK with nowadays as well (newsflash: it isn't).

Is this an attack on Spike, FrikaC and others? 

Just because you want something, doesn't mean your entitled to it. 

Funny enough, JKerman never replied this thread to clarify why he wanted to decompile the DOTM maps. People are just presuming things.

There are many reasons why someone would want to decompile something, including:
- To pass the work of others as their own (which is obviously immoral and illegal);
- To learn how to create something else that matches the technical specifications of the decompiled work;
- To perform maintenance on the decompiled work, fixing problems and providing quality-of-life improvements.
- To create derivative works, usually for fun.

If I was to bet, since he mentioned that he wanted to decompile the DOTM maps because they are "designed for the Kex engine", it seems he simply wants to learn how to make the KEX-specific features work, possibly to create new maps that takes full advantage of the new features in the KEX engine. Is this immoral? No. Is this illegal? No.

Now, hypothetically speaking about the other kinds of motivations mentioned:

Maintenance modifications are simply patches. In the case of a decompiled work, it's about patching the source and recompiling it. This is nothing new in Quake: the whole concept of vispatches is about decompiling the visportals of a BSP file and recompiling the visibility data to enable transparent water. Is this illegal? No. Is this immoral? That's debatable.

As for derivative works, both their legality and their morality depends on the license under which the original work was released on.

And looking at an example... The Operation Urth Majik readme doesn't have *any* mention of a license in it. No copyright information, no terms of use & redistribution, nothing. There's no explicit authorization, but there also isn't anything saying that it shouldn't be modified. In such a case, trying to contact the authors is advised, if they can still be reached.

But looking into the Wayback Machine... The OUM QC code WAS released:
These are the QuakeC files compiled for OUM. Are they not awful? Some are only there for reference porpoises and others (such as !AI.QC) are junked. Source mods include IKGuns and Custents, Dissolution of Eternity and one or two odd bits and bobs from the realm of Godnozwere.
The archived download link for the OUM source doesn't work because it was on FilePlanet. Is decompiling its progs.dat "not OK" in this case? Gimme a break. 

All this is just talk anyway. The Q21 stuff was clearly designed and released with the intent and knowledge that it would be hacked-on by the community. That's why it uses MD5s instead of a proprietary format. That's why it uses community-derived features and formats such as BSP2, LIT, wateralpha and fog in worldspawn, instead of proprietary solutions. They've even given us their full shader source code. The developers are active in community channels, they're aware this kind of thing is going on. 

The OUM QC code WAS released

Ok, cool. Now how about Quoth, where the below applies:

if somebody didn't share the source files, it probably was for a reason 

Fortunately we know the reason why the Quoth authors didn't share their QC source. It wasn't to prevent curious people looking at it, either. 

Ok, cool.

No, it's not cool. It's not cool to throw around blanket accusations condemning the action itself instead of specific instances of the action, when any problems with the action depends on the circumstances.

By doing that, you're just baiting people into feeling guilty and forcing anybody who ever decompiled anything to defend against that accusation, when it is YOU who should have justified your accusation and specified exactly WHO you are talking about, to not drag innocent people into the mud. 

It's actually cool as fuck to condemn the recently ongoing action, if the one example of its application not being malicious dates back to the Bush administration.

If you’re feeling guilty by doing something the author didn't intend you to do, that's fully on you. 

the one example of its application not being malicious

Grow a spine and say which malicious people you're talking about then. Otherwise you're just yelling at clouds. 

I literally mentioned the decompiling of Quoth in #20, but you gave up reading the post two words into it.