Black Mesa is the highly anticipated mod that brings the original Half-Life to the source engine. You may think that's pointless considering there is already a Half-Life: Source. You'd be wrong. This isn't just a straight conversion. Everything has been built anew, and many areas have been updated and changed. Considering Half-Life is meant to be one of the best PC games, and petty much spawned all these shooters you get nowadays I'd say this should be a definite download.
Even as a mod for a Valve engine, this has suffered from Valve time. First projected release date was in 2009, and then it had been in development for 5 years (2004). Rough development has delayed it, but it's finally here in all it's glory(minus Xen). It's success on greenlight and publicity has shown the community still wants this, and is shown by the sheer number of people trying to download it. It'll easily take a few hours to download.
Along with the mod, there is also a rather great soundtrack. You can get for free on the site (listed below), but with also the option of paying. The work that has gone into this, as well as the really high quality music, I'd say that it is something easily worth paying for.
Oh, and it's all free.
Find all the download sites here http://www.blackmesasource.com.







