As a big fan of the original Half-Life, it was revitalizing to get a good nostalgic feeling with Gordon Freeman & the science team. What's also great is that this game manages to add its own taste apart from HL1 with the immense detail and graphics improvement (especially Xen which was my favorite part). Black Mesa is one of those games that you'd wish you could erase your memory to get that first time experience again.
Crowbar Collective developed and published Black Mesa, a third-party remake of the original Half-Life built with the Source engine. It was first released as a free mod in September 2012, and Valve gave the go-ahead for a commercial release. The game's plot basically follows the original game's plot, The game follows Gordon Freeman, a theoretical physicist at the Black Mesa Research Facility. During an experiment with an alien crystal, a catastrophic resonance cascade occurs, opening portals to an alien dimension called Xen. Gordon must fight his way through the facility, facing alien creatures and military forces sent to contain the situation by any means necessary. Along the way, he encounters the enigmatic G-Man, who observes his progress. The game culminates in a showdown on Xen, where Gordon defeats the alien leader Nihilanth, effectively closing the portals and ending the alien invasion.
Definitely worth the money.