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.
Not only this mod has everything that the original game, it makes it better. It's rich in details, the music is great, everything was worked with mastery. The wait of years was completely paid off. I'd like to see a Half Life Episode 3 from these guys!