Run. Think. Shoot. Live. Source. Black Mesa is the Half-Life 2 total conversion of the original Half-Life game. Utilizing the Source engine and its endless array of possibilities and powers, Black Mesa will throw you into the world that started the Half-Life continuum and introduced Gordon Freeman to the world as a gun-toting, bullet-dodging Ph.D. in Theoretical Physics.
Really terrificly hi-def mod. I might go as far as saying it surpasses Portal2 for top visual quality in the Source engine.
I throughly approved of all the changes I noticed made to the original Half-life and actually wish they had gone further (nerfing some of the jumping puzzles for example). Mixing up when and where you got certain weapons kept things nicely fresh.
It would have been nice if they could have got some more voice actors involved. All the security guards sounding exactly the same was creeping me out...
I look forward to playing the Xen chapter(s) when they finally get around to releasing it.