As they always do, things in Steam are likely to change again. Unlike Valve's Steam Labs experiments for storefront discoverability or downstream effects of the upcoming Steam Deck, this one is a little more under the hood. As spotted by the unaffiliated Steam tracking site SteamDB, the beta version of Steam's client now has a new method that is capable of preventing users from accessing former builds of games they own. The majority of players likely aren't pulling up old game builds often, if ever, but this change could make life a lot tougher for modders, speedrunners, and anyone trying to roll back a buggy game update while they wait for a hotfix.
As explained by SteamDB's creator Pavel "xPaw" Djundik, this is what the newly added "GetManifestRequestCode" method does:
"This method takes app id, depot id, manifest id, branch name, and the branch password. All of these parameters have to match in the current app info for it to return a valid manifest code, if something mismatches, or you don't own the game it will return AccessDenied result. When a non-zero code is acquired, it is appended to the manifest download url. If a valid request code is provided, the manifest can be downloaded. Otherwise the content server returns an unauthorized error."
In slightly less technical terms, "it is no longer possible to download older game versions, because client asks for a code (GetManifestRequestCode) that rotates every five minutes," Djundik says.
As Djundik explains, this change only exists on the beta version of the Steam client right now. The change doesn't actually delete old builds from Steam's servers, or so they think, just limits customer access to them. It's not clear yet, Djundik says, whether Valve will actually enforce these manifest checks if and when they make it to the live version of the client.
There are reasons that Valve, and other developers, would understandably not want players to be able to roll back to old versions of games. Accessing pre-release builds that lack Denuvo DRM, Djundik points out, is one illicit use.
A lot of other activities could stand to suffer with the same move. If you've ever listened to the beginning of a speedrun during AGDQ, for instance, you'll often hear runners explain that they're playing on a particular version of a game to take advantage of an exploit or feature that was later patched out.
Preservation of old game builds is another potential victim. With live service games being as popular as they are now, that's a lot of potential loss for games whose physical spaces and features can change so drastically between updates. I'm not spelunking through old versions of, games myself, mind. Game archival remains a big project for the entire industry to reckon with though.
Developers will still be able to officially provide players access to alternate versions via beta branches within a game's Steam properties, fortunately. That isn't a very scalable solution for things like modding, speedrunning, and archival though.