One of my favorite documentaries was made by Noclip, which tells the story of Half-Life and Valve. It is soo good, a must watch. Interestingly, though, it features no one from Valve, as they, in typical Valve fashion, ignored their requests. https://www.youtube.com/watch?v=BQLEW1c-69c

So I'm very excited to watch this new documentary featuring people who worked on the game, made by the same people, such a surprise haha.