Oh, cool. I got thanked for something! :D
I read through the list and was like "Dang, I was going to mention Sonic 4 Episode I, Serious Sam 2, and Worms Pinball, but somebody beat me to it. Wish they were there when I was the one asking if they were DRM-free! X_X".
Yeah, I bought Sonic 4 Episode II hoping it might be DRM-free like the first game was, but it wasn't. I took a leap of faith on Serious Sam 2 (after it changed from "DRM-free" to "Steamworks" on GamersGate) when nobody else had an answer and found out it had to be activated on Steam in order to download it, but didn't actually have any DRM on Steam.
This list was a long time coming. I'd occasionally test what games were DRM-free, but never kept tabs of them and often forgot, because I'm careless and stupid like that. Likewise, I sometimes asked on Steam forums whether or not a game had Steam DRM. Predictably, the answers I received ran the gamut from "Steam isn't DRM" and "Steam is the least intrusive DRM (it's not)", to "No DRM, just Steam (unhelpful)" and "i haev report u obvius trol pirite".
Oftentimes, I would leave, and come back in a week or two hoping for an answer. Of course, there rarely ever is an answer, and the thread has devolved into morons arguing amongst themselves. Any attempts at a topic similar to this one on the Steam forums have proven worthless and futile, so it's great to finally have this topic here. Good work, bazilisek. :)
At any rate, I've tested (and retested to ensure nothing has changed since the last time I'd tested... and it hasn't!) a few games just now, and unfortunately all of them require Steam to run. :/
These all have DRM:
Atari: 80 Classic Games in One!* (Removed from Steam ages ago)
Avadon: The Black Fortress
Everyday Genius: SquareLogic (No longer on Steam. Should hopefully return, though.)
FTL: Faster Than Light
Geometry Wars: Retro Evolved
Railroad Tycoon 2: Platinum
Return to Castle Wolfenstein
*In "Atari: 80 Classic Games in One!", the bonus material viewer (Bonus Material.exe) has no DRM. All of the included Atari 2600 roms can be played through any Atari 2600 emulator, such as Stella. The arcade roms don't seem to be a standard MAME format, though. Strictly speaking, it has Steam DRM.
Last time I tried it, I recall Worms Crazy Golf has Steam DRM, too. It probably hasn't changed, but I'm done testing games for the moment. Pretty sure The Witcher required Steam, too. I might have remembered wrong, or it might have changed since then. Sorry I can't be more helpful, but I'm going to bed.
Post edited September 19, 2012 by Skunk