The prices of individual games are pretty bad. I'd rather track down a physical CD that I can keep forever and, where applicable, use one of the enhanced clients made from the GPLed source code. The big package of all of id Software's games is a deal, however, if you're cozy with Steam's tentacles.
Which brings me to my big concern: no more GPLed id Software games. Now that DOOM 3 is on Steam and theoretically available for sale forever, perpetually priced at $20, we probably won't see any source release as we've seen for everything since DOOM.
My naive understanding of Steam is that the General Cache Files (GCFs) encapsulate game data and present an extra layer between the user and the data. So Steam users might have to do some extra work to use a GPLed client with the data they've bought through Steam. Moreover, it's possible that id Software has now, or will someday, make it impossible for GPLed clients to play against the client distributed through Steam. I'm still unclear on how mods like Counter-strike and Red Orchestra work through Steam, but I'm guessing that they are close enough to commercial to get special status. (How do lesser mods integrate with Steam?)
Oh well. It was a nice run. Thanks for the games, John Carmack and id Software. Hope this venture works out for you.
Update: From Dustin over at LinuxGames:
Someone beat me to the question about Linux and open source gaming! Carmack is proud of the code he's released, and he will open source the DOOM III engine in the future, and years and years from now, id Tech 5. He also says that knowledge informs their decisions while developing new engine technology. This response got the biggest applause of the session so far, which kind of (pleasantly!) surprised me. :]There you go, Carmack's on record and I'm on track to be wrong. I hope he follows through.
Update 2: Be sure to check out Ryan's comments here and here which suggest I'm even more wrong.
I wouldn't say that it follows that they won't release the code - in general companies that have done GPL releases of their source code have not done a GPL of the data files. They still require you to own the game. I don't know that Doom specifically did that, but most of the releases I've seen are that way (wolfenstein, duke3d I know for sure).
Yes, I know the data's not GPLed, but I bet id will decline to release source and point to the Steam integration as a barrier to using third party clients.
Perhaps Carmack will stay with the spirit of the GPL because he thinks its The Right Thing, but I'm not holding my breath now.
RO isn't a mod, it is a full licensee of the ut2k4 (warfare?) engine.
Ostfront is a full copy of a modified Unreal Engine, in the same way that, say, Splinter Cell is. Tripwire is a full UE2 licensee. The mod version that requires UT2004 doesn't work with Steam (and, in fact, Ostfront is meant to be a different game, although you can see overlap from the original Red Orchesta mod).
It doesn't use the Steam SDK for accessing GCF files...it uses the existing Unreal file i/o routines, which means that Valve either ships you a Windows filesystem driver, or catches those calls or something. The game itself doesn't know that it's reading from a Steam archive, and I wouldn't be surprised if Doom/Quake/etc are similar.
Also, while I'm spilling technical information: Ostfront uses Unreal networking internally, not the Steam SDK. Besides handling buying, downloading and updating the game (all of which happens before you run the game executable) Steam's only used to validate players are legit (both in terms of DRM and Valve Anti-Cheat tech).
I would assume that Quake 3 on Steam talks to the standard Quake 3 master server and feeds standard Quake 3 packets between the game server and client, and Steam is just how the game gets onto your system in the first place.
In fact, I wouldn't be surprised if quake3.exe is the exact same one you'd get on a retail disc with the latest point release, and hasn't been linked to the Steam SDK at all.
Sorry but I love the move.
Steam is a great client with the tremendous advantage of "flattening" the non-gaming part of the gaming experience. I can play "Doom" or "Commander Keen" as easily on my new Vista PC as I can "Chuzzle" or "Half-Life 2".
I hope to see more classic DOS games get updated in this way. I'm sick of remembing DOS idiosyncrasies just to play "Alone in the Dark" or "Out of This World".