Analogue A Hate Story working without steam too.

Doing some more testing to add to your list :

Fable : The Lost Chapters
Sega Genesis / Megadrive Classics


Out of all my installed games currently those are the only other 2 that don't start the Steam Client. Will test when I install stuff to hopefully be able to add more to the list.

This thread was a good idea.

I see the Doom games, Hexen and Heretic are DRM free, Any idea on Quake 1?

Thanks to everyone for your contributions so far! The list is already longer than I thought it would be. I started systematically going through my library as well, but it's going to take time. Lots and lots of data to download.

I belive you can bypass the client requirement by firing up the game using the executable, in which case i'd assume the client is only tied to the launcher. I'm not sure and i can't verify it.

All Zombies Must Die - confirmed (the exe is called ShippingPC-Bzb2Game.exe)

A.R.E.S. - confirmed (you will get an error message that it can not find Steam, dismiss this and the game starts normally)

Yeah, I assumed this as well, which is why I put the question mark there (amok also didn't seem sure about it). I have F3 on Steam, so I'll get to it eventually.

I think the same is going to apply to other games with launchers. Which reminds me I forgot about the Space Quests.

Not sure about F3 yet no, and dont have it downloaded here and can't until later. If I remember correctly there where two executables for F3, one for the launcher and one for the game, the launcher was tied to Steam, but not the main game executable. This may have been fixed later though.

To help out, heres what I tested which loaded Steam to start :

Alan Wake & American Nightmare
Call of Cthulhu
Bully
Max Payne 1 & 2
Majest Gold & HD
Rogue Trooper
Zeno Clash
Hard Reset
Elder Scrolls Oblivion
Syberia
Tropico 3
C&C 3, 4 RA3 & Kanes Wrath
Alice Madness Returns
Bards Tale 2004
PoP Two Thrones & Warrior Within
Thief : Dark Shadows
Brothers in Arms Road to Hill 30
Dragon Age Ultimate Edition
Deus Ex Invisible War
Hitman 2 & Blood Money
Broken Sword 3 : Sleeping Dragon
Jade Empire
KOTOR
Divinity 2 : Dragon Knight Saga
Kaptain Brawe
Necrovision
Chrome
Doom 3 & ROE Expansion
FEAR 2
Stalker CoP
Wolfenstein & RTCW

Anything that has achievements you can scratch off immediately as that requires Steam, same goes for any Source based game. Looks also like any EA Bioware stuff won't go without the client running as every game I tested starts Steam and there are a fair few EA games in that list. Same can be said for Rockstar & Remedy stuff.

So anything on that list you are downloading to test just stop the download :)

Hope this helps out

Dungeons of Dreadmore has achievements.

Aromic Zombie Smasher - confirmed, must use atom_net.exe, atomiczombiesmasher.exe is tied to steam.

Awesome, thanks.
Nope. Dungeons of Dredmor for example has them, along with cloud saves and Workshop. Isaac has achievements too, but they are jury-rigged to the game in a pretty ridiculous manner.

And BEEP works without any problems.

Binding of Isaac also has achievements, but doesn't require Steam Client to run. Steam Achievements can be handled 2 ways, first way is the game tracks achievements, and when it connects to Steam it syncs, second way is that Steam tracks achievements, thus it won't catch any that you've done while it isn't running.