I've been trying to get Black Mesa Source working on my Mac for quite a while. At first glance the process seemed pretty hard and arduous but after some research and trial and error I got everything set up rather easily.

Here's what I did:

Download the game files, I used this magnet link. Extract the zip. It should contain BlackMesa-Setup.exe , BlackMesa.7z and BlackMesa.md5

Install WineSkin Winery

Run WineSkin, hit the "+" button and pick the latest CXG engine from the dropdown => Download and Install. Once that's done update the wrapper. Important note: Make sure the engine you use is CXG otherwise your game will constantly crash! (I used WS8WineCXG10.3.0 but if there's a newer version out by the time you're reading this then use that)

Click "Build new blank wrapper". Name it "WineSteam" or something. The wrapper will be saved to ~/Applications/Wineskin/

Decline the requests to install Gecko and Mono (they're not needed)

Once it's done, right click your wrapper => "Show package contents" and run Wineskin.app

Advanced => Tools => Winetricks => Update Winetricks

You'll want to run the following Winetricks: Notes: Don't change the Steam default install location when you get prompted, just click "Next" and uncheck the "Run Steam" box when it's done. Steam

d3dcompiler_43

d3dx9

d3dx9_43

d3dxof

ddr=gdi

multisampling=enabled (Optional: Enables anti aliasing ingame)

(Optional: Enables anti aliasing ingame) orm=fbo

psm=enabled

vcrun2005

vsm=hardware

win7

Once all that's done close the Winetricks window. You should now be back under the "Tools" tab of the Wineskin Advanced settings window. Switch to the "Configuration" tab and set the "Windows EXE" to /Program Files/Steam/Steam.exe

Close the Advanced ettings window. You should now be on the Wineskin main menu window. Click "Install Software". Point the setup executable to the BlackMesa-Setup.exe file that you downloaded earlier. When it's done make sure to uncheck the "Run Black Mesa" box and ignore the warning dialog that comes after it (about no new executables being installed)

Run your wrapper (which should be at ~/Application/Wineskin/WineSteam.app ) and you should see Black Mesa in your library. Hit play and install the Source SDK Base 2007.