Black Mesa source Maps

This download looks like an addon. You need to extract the downloaded zip and put the addon folder in your Garry's Mod addons folder. You should end up with a directory structure similar to below:

• steamapps
  • common
    • garrysmod
      • garrysmod
        • addons
          • BMS maps <-- Addon folder!
            • e.g.
            • lua
            • maps
            • materials
            • models
            • etc

• BMS maps/
  • bms_anomalous_whole.bsp
  • bms_c1a0.bsp
  • bms_c1a2.bsp
  • bms_c1a3.bsp
  • bms_c1a3a.bsp
  • bms_c2a5_r3.bsp
  • bms_c3a1.bsp
  • bms_c3a1a.bsp
  • bms_c3a2d.bsp
  • bms_test_map.bsp
  • c0a0_rm8.bsp
  • c0a0a_cavesb.bsp
  • c1a4d.bsp
  • c3a2e.bsp
  • c3a2e-edited.bsp
  • dm_crossfire_06.bsp
  • gasworks_07.bsp
  • gasworks_08.bsp
  • lambda3.bsp
  • READ ME.txt

blackcrawler61, fran309, jorens565, jin130920, jin130920, shrekisC001, Mr_Random, BarneySDK, ino, chawqiben9, ferrebussantiago2009, 19914602909, Sundowner, Mr.Racism, JuanDMHL25, italnegrini, dominiccoronado09, husnuyigitkus1225, korylopez870, [TRC]RASCAL, yitzhakomar, NekoLare, masascuate666, Hack007, koziutek1 lolo, m.popeniuk, 老徐之才, 老徐之才, yelitzacarolina, xxxx, brayanhogermozza, amir47, Flow_cat, Termor, forbesmax01, dangerzachattack, 盗号+2898504165, 盗号+2898504165, 盗号+2898504165, Paisen, LoomRez, Veronicascorrano, Roxieboy16, DeclanDude25, ilyadymna, derricyoungthereal, e.soutiran, KoZy7, aidamirmamiy, oooooofenstein +399 others