The source community seems to be flourishing with creative talent, having several released mods and also several projects that are being worked on.
One of them is Black mesa that seems to never be released or at least not in a reasonable amount of time.

Another mod have lately caught my attention; it’s named opposing force 2 and is an unofficial sequel to the critically acclaimed first opposing force, which also well received by the general public.
They have just released a demo that can be downloaded trough their site.
I have sadly not gotten a chance to play it myself but will do so next week, the game looks promising as most things centered around the hl universe. I hope some of you guys will try it and also like it. (you'll need a source game to actually play it)

http://www.moddb.com/mods/opposing-force-2
http://www.of2mod.com/

......aaaaaaaand yet another mediocre game.

Well since it's a sequel, they don't really have the possibility to wander away all that far from the HL franchise, meaning the game have all the possibilities to be great

This mod actually has professionals working on it, the one you posted looks absolutely terrible. And the odds of this one actually being finished is much higher. Quality is much better as well.

Whoops, sorry, forgot the link:

http://www.moddb.com/mods/operation-black-mesa

.......aaaaand yet another mediocre bughunt.

We'll just have to see what the future hold for us, which mod that gets realesed and all of that, anyway I'm looking forward to all of them and thanks for the link Rang3r1_v2

http://team-blur-games.com/overdose/

Looks promising...

This is PR genius right here. It's still way too early to tell, but it seriously looks promising. I'm longing for some gameplay footage now!