Since its release in November of 2004, Half-Life 2 has been a fan favorite and has only gained impassioned fans as time has gone on. However, after the release of Half-Life 2: Episode Two in October of 2007, Valve failed to complete release its 3rd Episode and the once highly anticipated Half-Life 3. Valve is now celebrating its 20th anniversary for the release of Half-Life 2 by sharing the experience of making the game in a documentary on their YouTube channel. In it, Valve founder Gabe Newell speaks on what kept him from creating Episode 3.

I couldn’t figure out why doing Episode 3 was pushing anything forward.

You can’t get lazy and say, ‘Oh, we’re moving the story forward. That’s copping out of your obligation to gamers. Yes, of course they love the story. They love many, many aspects of it. But saying that your reason to do it is because people want to know what happens next, you know—we could’ve shipped it, it wouldn’t have been that hard. The failure, my personal failure was being stumped. I couldn’t figure out why doing Episode 3 was pushing anything forward.

Half-Life 2 level designer, David Riller, spoke about how the team were struggling with “element fatigue” and needed to “go bigger or do something else.”

I think we had really explored a lot of what made sense in the Half-Life universe and setting.

An engineer by the name, David Speyrer, said it was “tragic and almost comical” that, after Valve released Left 4 Dead, the team felt like they missed their opportunity to release Episode 3 and now needed a new engine to continue the franchise.

That just seems in hindsight so wrong. We could’ve definitely gone back and spent two years to make Episode 3.

Half-Life 2 will forever be a reminder of what could’ve been and fans will just have to enjoy what they have for the time being.