That's pretty shaky ground too, even if you can overlook the foundation being closed source, Valve aren't really known for supporting their engines very well beyond their own internal needs. They're not trying to be Epic or Unity.
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 aren't really known for supporting their engines very well beyond their own internal needs.
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.
That was then, in 2025 they don't have a public Source 2 SDK, nor do they generally license the engine to third parties, S&box being the sole exception. They barely have their toes in the middleware game anymore.
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.
S&B existing and being what it is, effectively makes it the Source 2 SDK, although it's not from Valve. But fair point Source 2 isn't licensed to others, I think the expectation is that if you wanna build a Source 2 game, you have to use S&B. At least for now, who knows what their ideas and ambitions really lie.
>They barely have their toes in the middleware game anymore.
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.
There are various internal Valve tools that aren't available in any Valve-published SDK, but are in (accidentally?) within Dino D-Day's, a third party game based on Portal 2's version of Source.
> Valve aren't really known for supporting their engines very well beyond their own internal needs
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.
Oh right, that's more reassuring. I guess you'd still have to cut a deal with Valve to use FPs fork commercially though? Which is a wildcard since the licensing terms aren't public as far as I can tell.
There is already a deal between Valve and Facepunch. I don't know all the terms but you will need to publish your game to Steam (not exclusively).
https://sbox.game/dev/doc/systems/game-exporting/ (bottom of page)
Not sure if this was added after your comment, but it now says (in a scary red box)
> 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?
that's pretty vague, I mean are there no real licensing terms somewhere? What am I truly signing up for when I try to use this engine? I have to publish my game on steam but in what form? Same price as I do on my own website/store? Same exact form as on other stores? Same exact time, I can't publish first on epic and only later on steam?
I doubt its much of a deal. Garrys Mod and Rust have both been wildly successful (which means Valve has made tons of money off them as well)
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!
Dude. People are playing and making Gmod and HL2 mods and maps to this day. How many 20+yo game engines can say the same?