Why is Black Mesa a "non-steam mod"?

Im wondering that Black Mesa is a non-steam game. In steam Library ist declared as a “non-steam mod”.

As far as i understand that means that it wont show my achiements, nor got any updates/patches via steam?

Why is that so? Isnt there some kind of cooperation since its using the source engine and stuff?

As far as I know, it was Greenlit and all… perhaps Steam doesn’t fully support it yet?

It hasn’t been integrated with steam, so achievements will not be officially registered and they can’t update trough it yet. It has been greenlit but integration takes time.

Only games officially put onto Steam for purchase/download by Valve will support out-of-game achievement displays and automatic updates etc. All Steam does is offer a convenienent, organised way to launch and play mods.

It’s not very different to when you add a non-Steam game you bought on a disc or downloaded from elsewhere to your library, just to have a shortcut and overlay functionality.

Have patience, it’s already great they have the greenlit status

Black Mesa will be available through Steam at a date TBD.

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.