Space Station 13

After three years of development, and rising from the ashes of at least a dozen failed attempts, the dedicated team lead by DooblyNoobly has released a public alpha for Windows, Linux and Macintosh. Right here, right now, no paywall or nagware or nonsense.

https://unitystation.org/

Obviously a long way remains to go before Unitystation has all the bells and whistles we're used to. But now the road to "beyond BYOND" is finally open.