Valve are always upgrading the Steam store and it appears another new feature has begun rolling out, at least in a limited form with official playtests.
Currently, if developers want to let people try the game before release they hand out special Beta keys. It's a messy system, and has in the past caused all sorts of issues with Beta keys being handed out incorrectly with keys being revoked that shouldn't have been and more. It's taken a long time, around five years or so since hints of it appeared but they've now apparently shipped a new 'Playtest' feature on Steam.
Noticed by xPaw on Twitter, the creator of the super useful SteamDB website, it seems the first title to use it is Total War: ELYSIUM. It has a dedication button on the store page allowing you to register your Steam account for a Playtest.
This could certainly streamline how developers let people access games early, if it becomes widely available. Steam has been a lot more than just a games store for quite some time now and features like this seem pretty obvious to add in. What do you think?