How do I get it?
s&box is available on Steam for $20.
Are you using workshop?
No. We've made a system where you don't have to install addons. This is what sbox.game is. In the same way, you don't have to install videos from YouTube; you just download what you need.
Why not Unity? Why not UE?
We're sentimental about the Source engine. Source 2 has a beautiful renderer and brings the engine up to date with tools like ModelDoc and Animgraph.
It would have been cheaper and easier to do this all on Unity or UE, but we would have loved it less.
Will creators be able to monetize?
Yes. It's integral. We owe our entire business to the fact that Valve let us monetize.
Right now there are two ways for our creators to make money. You can make a cosmetic item, which then goes for sale in game and you get a cut of it via Steam Workshop. Or you can make a game and get a cut of the playfund.
We want to be careful about pushing further. We want you to be able to charge for whatever you want, but we also don't want everything to become pay-to-win like on other platforms.
So is it an engine, or a platform?
It's everything. An explanation was posted on this blog here.