A series of maps based in black mesa made back in 2007 for the half-life gold engine.
Half-life: Black Mesa Missions 2007By Mapster
=Instillation=
1. copy hl_blackmesa2007.wad into the following directory:
Steam\SteamApps\Account\half-life\valve
2. Copy all remaining files into the following directory
Steam\SteamApps\\Account\half-life\valve\maps
=How to play=
1. Load half-life
2. Press ~ for console and type in the following line.map
hl_bm_map1
3. Enjoy.