[snoutie]

Then again there is s&box which I would not consider being close to either, well the games that can be made with s&box at least. But I agree that it would probably be hard to build something like Teardown inside the Source 2 Engine. On the other hand: Teardown does not use Unity either.

[jsheard]

S&box licensing Source 2 is a bit of an enigma to me, I get the impression that they're having to rewrite huge swaths of the engine so I don't know what they're getting out of it. They've gone to the lengths of integrating C# scripting from scratch rather than using the scripting facilities that Source 2 comes with. Nobody else has licensed Source 2 in the 4 years since s&box adopted it, so they're the lone outlier in any case.

Respawns use of Source 1 was a similar story, they ended up rewriting practically everything in the course of developing Titanfall and Apex Legends, to the point that it's almost unrecognisable as Source at this point.

[jna_sh]

I don’t think there is (or needs to be) much more to it than Garry’s personal history and success with Source

[Rohansi]

S&box has rewritten many parts of the engine in C# at this point. Gets rid of lots of legacy code and makes this easier to change in the future. Using the scripting facilities built into Source 2 would have restricted what could be written in C# and slowed the team down.

If you haven't taken a look at S&box recently it's looking a lot more like Unity now. https://sbox.game/news/scene-system

[meibo]

Garry has publicly expressed regret over choosing Source 2 for this reason, but they might be in too deep now. Generally, the tooling is really great, so I guess that's the primary benefit.