Black Mesa

Black Mesa is a fan-made mod gone commercial that beautifully recreated the entirety of the original Half-Life in the Source engine.

The original Half-Life is well-regarded as one of the best first-person shooters out there, but it's long needed a proper remastered edition. Although fans had hoped Valve would do something with the debut of the Source Engine, it was a group of modders that made it happen.

These modders put the game together over the course of more than a decade, eventually releasing it on Steam as a commercial product. Now you can enjoy the original Half-Life experience with a shiny, new engine and modern graphics!

From the Black Mesa Steam Store page: