This is our attempt to create a worthy Garry's Mod sequel.
We've been playing with it for a long time. It started off on the Unreal Engine, but now it's being developed on Source 2.
It's not going to be Garry's Mod 2. It will eclipse what is possible in Garry's Mod rather than simply be a modern version of it.
The current status is "heavy development". Some people already have access. Our plan is to get to a releasable state over the next 6-12 months then improve it over 10-20 years.