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.
Honestly, I'm not a huge fan of the half-life games personally, but I put a few hours into this just out of curiosity and what they've done here is extremely impressive. I wish I'd been a bigger Half Life fan just so I could have enjoyed this game more. I will, however, be trying to find a good Let's Play of it at some point so someone much more into the game can point out all the cool Easter eggs and such for me.