https://www.pcgamer.com/black-mesas-xen-chapters-in-final-polish/

Stop me if you think you've heard this one before: Half-Life remake Black Mesa's Xen chapters should be out very soon. You may well be sceptical—Xen has been delayed multiple times—but in an update this week the developers said that the five chapters are going through external playtesting, and two of them are pretty much "locked in".

The first chapter, itself called Xen, is mostly done, and the team need to simply "polish one or two rough edges". The third chapter, Interloper, is playable from start to finish, and the final chapter, Endgame, is locked, and just needs some final minor tweaks. "There are some dependency assets and some polish we have to implement once the rest of the game is complete, but other than that, it is ready to go."