How to fix "Could not load library client." ->

If you're having trouble with the "Could not load library client." error, here's a potential fix:

Go to "C:\Program Files\Steam\SteamApps\sourcemods\BMS" (this location may vary, for detailed instructions, see Note 3).
Open "gameinfo.txt".
Scroll down to "FileSystem".
Change "SteamAppId 218" to "SteamAppId 215" (without "").
Save and close the file.
Exit and restart Steam.
Once Steam has restarted, there should be a "Black Mesa" entry in the library (All Games).
Click "Play".
If it launches without any error, enjoy! If the error still persists: Exit Steam and proceed to the next step.
Go to "C:\Program Files\Steam\SteamApps\sourcemods\BMS", again.
Open "gameinfo.txt".
Scroll down to "FileSystem".
Change "SteamAppId 215" to "SteamAppId 218".
Save and close the file.
Exit (if you haven't already), restart Steam and play the game afterwards by clicking "Play" in the library (All Games).


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Note: This one did work for me, fortunately, but please remember, this may or may not work for you and I guarantee for nothing, thank you!

If it does work, however: Happy shooting!

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Note 2: Simply restarting Steam after installing the game could help, too. If I were able to recreate the scenario again, I'd try to see if restarting is a possibility, but since I can't: Feel free to drop some feedback!

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Note 3:

Windows Vista / Windows 7: To find the mod's location, simply type "BMS" or "sourcemods" (without "") in your startmenu's searchfield and open the corresponding folder.

Windows XP: To find the mod's location on a Windows XP system, open your startmenu and start the "Search" program, then select "All files and folders", type "BMS" or "sourcemods" (without "") in the top searchfield and hit ENTER or just click "Search" and open one of the folders.

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Thanks for reading, if you have any questions or just wish to confirm that the provided solution is working, please reply below!

Oh, and I did register on the forums, just to share this "fix" ,

- Jenova

EDIT (08:54 AM): If you're still struggling, try validating and / or defragmenting the Steam Cache Files for those 3 "Tools":
Source SDK
Source SDK Base 2006
Source SDK Base 2007