valve is at ~360 employees right now. considering a good chunk work at steam or VR games and that new card game. how many are realistically working on HL3?. we have no indication that they are neither am I creating the thread about an ongoing HL3 development because its unlikely
but valve in my opinion. doesn't have the staff to make a modern HL3. it would take all of valve's employees to make HL3 in probably like 5-7 years. so I doubt they worked on it at all.
a game like HL3 needs a big studio that is the size of valve to make it. if valve was 100% free of anything except making half life. which is not the case.