It depends on Source 2, which is not open source.
The most obvious aspect to that is that Source 2 doesn't support consoles. Valve don't need it, so they didn't implement it.
Valve has a long history of supporting the modding community and outside users of Source, not sure where you're getting your information from but I don't think they've worked with the Source engine before. One of the biggest and most popular mods of all time was built on Source, and took the world by storm, with pretty big support by Valve through the years as well. Eventually they even bought the whole IP.
Even when they were more open with their tech it was on the basis of "you can play with the tools we used to make Half Life and if your idea is sufficiently Half Life shaped then it will probably work", not trying to be a general purpose toolkit a la Unity.
Well they do have Steam Audio but yeah I agree. I think Epic is much better in this space, even though its only source available in practice they do a lot to support engine modifications and also accept external PRs. I think Valve has a lot to gain from open sourcing Source 2 and they should realize how important modding was to their initial success. The issue is now they can just print money with Steam so there is no need to invest in modding support.
They don't need to. S&box uses a fork of Source 2 that is maintained by Facepunch, with Valve's upstream changes merged in as needed.
My point is, if I were Valve id let Garry run wild with my engine--no deal needed. Hes proven himself more than once. Just a thought!
https://sbox.game/dev/doc/systems/game-exporting/ (bottom of page)
> You can export your game, but you shouldn't distribute your exported game just yet.
That doesn't sound good, maybe they realized after the fact that they haven't actually worked things out with Valve?
All of their games (Dota 2, CS, and the other ones they hardly maintain anymore) are basically just passion projects at this point, lingering on from a bygone age when they were a game development company.
Their most recent title, Half-Life: Alyx, probably only got greenlit because someone internally was able to convince leadership that it would help sell VR headsets.
In any case, my point was not that these games make no money, but simply that Valve doesn't need them. The total number of people buying games on Steam vastly dwarfs the number of people who play Dota 2 and CS2 (even just counting total players - how much more when you narrow down to players who spend money).