Thank you, this is very helpfull for some games that I got for free on Steam (.
the problem is that the only one I really was interested to get "Drm- not totally free" was.... Bioshock Infinite... that use CEG... that unfortunate.

Does anyone know if Tales of Zestiria will work with this? I've heard it has traces of Securom in it, so I guess it's a no?

This method mostly only works with "DRM-free'ish" Steam games, as in mostly indy and some few others. (often available DRM-free on GoG or other shops).

It's very unlikely it will work on a recent non-indy game especially one coming from Bandai Namco. (the same B.N. that just put an extra layer of DRM/anti-tamper on the just recently released 10+ years old Tales of Symphonia)

For what it's worth, this is just as easy to do in Linux, and no Linux Steam games use CEG. I waited to buy BioShock Infinite, XCOM, and Spec Ops: The Line until the Linux versions came out, and I couldn't be happier.

This method works with ANY games that only use the Steam client as the DRM. I have dozens of triple-A games like that, and they all work; all three Dark Souls titles, The Evil Within, The Witness, Rocket League, and a bunch of others are all fine. Heck, Street Fighter V works, and that's BRAND new.

EDIT: Tested with Dark Souls III, a Bandai Namco game, and it works perfectly.

Hey, thank you for having done this tutorial!

I've found a post that should be relevant to this discussion :
https://steamcommunity.com/discussions/forum/10/626329186734280459/#c626329186744697589

Ha, holy crap, that reply is from a Steam discussion thread that I started! :-D

Thank you for posting this. I'm trying this out right now.

This doesn't work "forever". Eventually, maybe after a month but usually 3-6 months (possibly longer) of being offline without any kind of internet connection, Steam will want you to sign in online and/or renew your password. Happens everytime. I learned this from moving my account from my old Voodoo Firebird to my Alienware M17 a couple years back. Steam has some kind of built in feature where it either "times-out" after a long time of being off-line or it secretly connects in the background from time to time to let Steam know how many computers your account is being used on, probably both. To truly play offline FOREVER you have to know about this feature of Steam and find some way around it, which I have not.

Pretty close, though. I've had one laptop in offline mode for over four years now. It's an older, slower laptop, and doesn't have any of the nice new games on it, but it's adequate for Windows XP and a bunch of good, old games ( >.> ). Steam prompts me to log on and install client updates every time the laptop boots, but all I have to do is close that window and Steam keeps on doing its thing. Your problem was migrating things to a new computer, which totally changes the problem. Of course Steam has to go online for the games which are DRMed to a single account. That should be obvious. If you keep your stuff on one computer (physical or virtual...) it should be good for a long time.

Close enough to forever. Ain't nobody going four years without an internet connection these days ^_^

Steam's Offline Mode works indefinitely. It used to have a bug that required revalidation online, but that was indeed a bug, and it was fixed a while back.

Sorry for the necro, but thanks for the info, VERY APPRECIATED. I always asked myself if there was a way to check if a game has CEG or not.

Very important for me, when I end up buying games on steam which are unlikely to get released here (devil may cry, dark souls and so on).

I just tried this myself. I can't believe it works. This blows my mind!

*necrovivify*

If you are still around, OP, can you confirm how long your new offline computer was not connected?
Can a third-party confirm this?
Which means that when (with built-in obsolescence) the hardware dies, the games must be re-verified by Steam.
Try me. :P

It does work forever. Sure, there is no absolute guarantee that the client doesn't have a builtin expiration date of several years, but it seems very unlikely.

I've just tested an old steam client backup with some game backups of the same date from November 2019 (nearly 2 years ago) on another offline non-steam pc. To make the situation more diffcult, the backup is from a windows 7 machine while the test pc has windows 10.
Result: It works perfectly.

I've also tested a recent client backup with old game backups and they work perfectly too. So the client obviously doesn't check the game's "age". Though I would definitely advise to backup the client often, since you never know if Valve will change sth. in the future.

Btw. here are some important tips, that are not covered in the initial post:
-to disable the client's check for updates on start, which can prevent offline mode from working, create a "steam.cfg" in the Steam folder and add the following lines -to start in offline mode automatically and skip the annoying offline mode warning, add/change the following lines in your "config/loginusers.vdf" -the client backup should not only include the Steam folder but also the registry entries steam creates: -> those contain login information and info about the redistributables (directx etc) needed for some games
-> restoring these allows the automatic login into offline mode and skips the redistributables installation (off course make sure that everything is installed beforehand)

-if you (accidently) change the activation of a dlc or the game language for a game in the client, it wants to update the game online. You can revert this if you restore the game's appmanifest*.acf from backup and/or make sure that "StateFlags" is set to "4" in the appmanifest file. This tells the client that the game is fully downloaded and doesn't need to be updated.

PS: If there is interest I will also post my client blackup and start scripts that automates these things.

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edit: corrected some info in the tips section
edit: as requested:

So here are the (simplified) batch scripts I'm using. Nothing fancy, but it gets the job done.
(for additional info, see the comments in the scripts)

SteamBackup.cmd:
-uses 7z to zip the client without game data and exports Steam registry keys
-paths to Steam, Backupfolder and 7z must be set correctly in the configuration section

SteamStart.cmd:
-paths to Steam must be set correctly in the configuration section
-place steam.cfg_offline, your own modified loginusers.vdf_offline and loginusers.vdf_online into the folder where the script resides
-make a shortcut to SteamStart.cmd with "offline" or "online" (without quotation marks) as argument to start steam accordingly

Btw, even some games WITH a ceg entry on steamdb.info work fine with this method. For example you can play the single player of Left 4 Dead 2 without problem. Also Dishonored or The Talos Principle should work, but since I rebought these games here, I have no backups anymore to try it again.