0 good answers in here honestly.
If HL3 is real it would need to:
-Look better then every game out in existence
-Have insane physics
-Unique gameplay
-Top notch everything (animation, performance, lighting, music, atmosphere, etc)
It’s exactly why we won’t get it. Gabe is right . They took too long and the bar for what hl3 needs to be is so high they would never live up to it now.