Black Mesa

Black Mesa (formerly Black Mesa: Source) is a Half-Life 2 total conversion remaking of Valve Software's award-winning PC game, Half-Life.
Utilizing the Source engine, Black Mesa will reintroduce the player as Doctor Gordon Freeman, along with the original cast of memorable characters and environments seen in Half-Life.

Black Mesa was built and founded on the basis that Half-Life: Source didn't fully live up to the potential of a Source engine port of Half-Life.