HL3 would not have provided closure. Marc Laidlaw (Valve) – Interview

snip “I will say that I expected every installment would end without resolution, forever and ever…But it would still end like HL1 and HL2, with Gordon in an indeterminate space, on hold, waiting for the next game to begin. So one cliffhanger after another.”
Looks like they succeeded.

I like Laidlaw in interviews. He’s quite candid, to the point, and occasionally quite funny.

I’m still mad at Valve for not finishing the plot, and for prioritizing VR and Dota over the games that made them a household name. But I’m bitter and old and Valve are quite happy with their billions from Steam, I’m sure.

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.