I played Half-Life remake Black Mesa, and really liked it! I also in the intervening years completely forgot that it wasn’t technically finished, since it ended on Earth and not, as the original game did, on the alien planet Xen.
https://lastchance.cc/black-mesa-the-kotaku-review-5944812%3C/a%3E%3C/p%3E
That vision is almost done. The team have said todaythat their version of Xen will be out in December, a release window they say is a “a do-or-die deadline” (it was supposed to be out around now). In addition to this new final chapter to Gordon’s original adventure, they’re also making a few changes to the existing game like a new dynamic lighting system (see below) and some colour correction.
Note that the new Xen will only be made available to those who own the the paid version of Black Mesa (released a couple of years ago).