Black Mesa, the Half-Life fan-made recreation continues progressing towards finally releasing the delayed Xen levels.
The latest update, posted late last month shows off some rather impressive new stuff coming to the game. Using the system they developed for their Dynamic Lights, they've now included Screenspace Fog. It's light on resources and does look rather good:
They've also improved the AI for the "Alien Grunts" to make them much more unpredictable and challenging. They will "leap onto different platforms, find a way to outflank you, get in your face, and unleash a devastating secondary "hornet hurricane" attack"—scary!
They also improved the Alien Controller NPC, turning them essentially into "a kind of overlord or mini-boss". The Vortigaunt NPC was improved as well, flashlight shadows are back, Soft Particles are now working and a few other bits.
Lastly, they note about they progress specifically on the Xen levels and it sounds like progress is really good. Sounds like quite a bit of work still ahead though but it does sound exciting.