How many people are playing Half-Life: Source right now?

Half-Life: Source has 19 players on Steam right now, with a 24-hour peak of 41 and an all-time peak of 623 on Jan 2020.

What is the all-time peak player count of Half-Life: Source?

623 concurrent players on Jan 2020.

Half-Life: Source was released on Steam on 1 Jun 2004.

Parent, children and the same developer