This seems to be turning into a Linux gaming blog, and there's probably no stopping it, so I might as well not even try.
So, hey, the classic Doom games on Steam got updated to include those official Unity engine ports. That's cool. I mean, I guess it's cool. I'll defer to the video by GmanLives on YouTube for what's actually cool about it:
Update: It seems GmanLives has made the above video private, for some reason. Uh, okay...? Whatever. You don't need to watch this video before reading anything that follows. It was just a general overview of the Unity ports of the classic Doom games, and apparently some people disagreed with the opinions therein, but I don't remember any part of it being so controversial as to warrant removal.
It was thanks to GmanLives that I even found out about the updates to my Steam copies of these games. I go back to Doom and Doom II somewhat frequently, and in fact I do play the copies I bought from Steam, but I don't typically launch them through Steam. Last time I installed them, I immediately copied the WAD files out of the Steam folders to use them with GZDoom and then uninstalled the Steam copies. Therefore I don't often look at these games in my Steam library, and therefore didn't see the big "MAJOR UPDATE" notices, which I now see have been there since September 3rd.
So I was a bit excited when I heard that the Unity ports had come to Steam a week prior, because I thought I might be able to play the No Rest for the Living expansion for Doom II, which had previously been available on Steam only via Doom 3: BFG Edition, which I'm not going to buy because I already have regular old Doom 3. However, once I launched the game, I saw that the Unity version of Doom II includes only Hell on Earth and Master Levels by default. I think you can get No Rest for the Living as an official add-on, but that seems to require a Bethesda account. Maybe I'll create one. Maybe I'll download the WAD from elsewhere. I would rather play any add-on WADs in GZDoom anyway.
The real disappointment — and I'm fully aware that I'm nitpicking here — is that the inclusion of the Unity versions technically breaks the out-of-the-box Proton compatibility of Steam's The Ultimate Doom and Doom II: Hell on Earth on Linux. That's not a tragedy, because they can still be made to run on Linux quite easily. However, it's not a good look for Proton, because both games were whitelisted by Valve for Proton 3.7-8, and that whitelisting is now incorrectly applied to the Unity ports because they were added as updates to the existing games instead of showing up in users' libraries as separate items. Steam for Linux will launch the Unity ports with Proton 3.7-8 by default, and it won't work. Valve whitelisted these games only on the basis of their DOSBox-powered versions running well with that version of Proton.
Of course, using Proton to run the classic Doom games in the Windows version of DOSBox is a bit of a joke. You'll have a better experience running them in a natively Linux-compatible source port like GZDoom. If you really want to run them in DOSBox, there's a native Linux version of that too (and you can make Steam use it for DOS games by installing the compatibility tool Boxtron), so there's no good reason to run the Windows version of DOSBox in Proton. Nonetheless, Valve whitelisted the games for Proton 3.7-8 based on the fact that their old DOSBox-powered versions, in spite of themselves, did work perfectly in Proton 3.7-8 (and, in theory, still should). The new Unity versions don't run with Proton 3.7-8, nor do they work with the current version, Proton 5.0-9. They do seem to work perfectly with Proton 5.9-GE-5-ST, a fork of Proton which is not included in Steam by default but which is easy to install. So if you want to play the Unity ports on Linux, it requires only minimal effort.
The real problem here is that someone is bound to see "Proton 3.7-8 selected by Valve testing" on the newly updated classic Doom games and understandably assume the default versions of the games will run with Proton 3.7-8 out of the box. Now that the default versions are the Unity ports, that's not the case. When you launch either The Ultimate Doom or Doom II: Hell on Earth in Steam now, you will be presented with the option to run either the Unity version (which is the default) or the DOS version, and the default Proton version selected by Valve itself is good only for the DOS version which is now relegated to a secondary or extra option.
The other problem is that, because the Unity versions don't show up as separate games in the Steam library, you can't select different compatibility tools for the DOS and Unity versions. These versions being combined is good in general for those who don't want cluttered libraries, but preliminary testing on my own machine suggests that the DOSBox-powered version of The Ultimate Doom doesn't want to run using Proton 5.9-GE-5-ST which is the only way I know how to run the Unity version. If this is true and it's not just me, alternating between the two versions would require changing the game's compatibility settings each time. I suppose most people, upon deciding which version of the game they prefer, would just stick with it. Still, this bugs me.
Even if there is a Proton version which runs both DOSBox and the Unity ports, I still maintain that using Proton is sub-optimal for the DOSBox-powered versions anyway, and one should really be using Luxtorpeda as an alternative to Proton. Luxtorpeda runs the Steam versions of the classic Doom games in GZDoom automatically, and I probably would have used Luxtorpeda if I hadn't already set up GZDoom manually before I knew Luxtorpeda existed. However, selecting Luxtorpeda as a compatibility tool for The Ultimate Doom would work only for the classic DOS version; it wouldn't be able to run the Unity port. You can't select a single compatibility tool which runs both versions optimally, and you can't select separate compatibility tools for different modes of running a single entry in the Steam library.
In short, I'm slightly annoyed. I'm still just going to keep using GZDoom to run the original WADs anyway, so I guess you could say I'm annoyed on behalf of anyone who hasn't already figured this out. But I guess it's reasonable to assume that anyone who can't figure it out probably lacks the patience for playing games on Linux in the first place.
