Black Mesa : Source as it is to be known combines the deep, rich story of the original with graphics that take full advantage of the Source Engine. Custom, High-resolution textures, custom models, detailed environments all aim to create to ultimate immersive half-life experience (Yes the Crowbar still looks cool)
Now... do you want to know the best part?
Having recently switched from the Counter Strike : Source Engine to the Team Fortress II engine all you need to play it is a Steam account and any other game that uses the Source Engine. Sounds like a win-win situation to me.
There are now Three types of gameplay. Single Player where you take control of Gordon Freeman, Co-op where you bring a friend in and he takes control of various Scientists and Security Guards and the good old fashioned Deathmatch mode.
A trailer and a teaser have been released and are available for download at the Black Mesa : Source official website. The game is due for release next year.
More info to come later. The official site is currently experiencing a high level of traffic.
Source (lol puns) : Offical Website through the official Steam community Page