We reported back in November last year that Black Mesa, the 12 year old project to update Half-Life 1, was finally nearing it's final hurdle, adding Xen to the game. That was later pushed back to December last year, and then pushed back further again - but the good news is that the game has now finally released, albeit on Steam Early Access.
Xen was previously available as a beta, with only a few levels playable, but the full release on Steam allows players to enjoy every level within the game. To celebrate, it's also available at a 20% discount right now.
In an update, the developers said;
We have pushed a major patch to the Xen levels and released the full game on Steam “mainline”. This means you can play a polished and tested version of all Black Mesa without having to switch into public-beta. If you have been holding out for Xen, this is what you have been waiting for!
The next update will bring the game out of Early Access, so the project is nearing the end of development at this point. There will still be changes while in early access, though, although mainly to fit and finish, with achievements also promised for the full release.
You can check out the full details here and grab the game here.