After sitting on the wavelength irc channel, and getting almost 5 questions a day on the same subject, I finally found some time and wrote this guide to debugging your project. This guide works for either the server .dll or the client .dll, so you can apply the same steps to both projects and it will work. Thanks to Robin Walker for kicking my ass and making me do this, it was needed.   Open your HL SDK Workspace. Go to Build - Set Active Configuration Set the Active Configuration to Debug Hit ALT-F7 to go to your Project Settings Go to the Debug Tab, now: Where it says "Executable for debug session" point it to your hl.exe Where it says "Working Directory" set it to you Half-Life dir Where it says "Programm Arguments" set your command line parameters there. I use: -game frontline -developer -console -sw NOTE: -sw runs HL in a window, so if you got a old Voodoo based card, the only way you can run it in a window is by running software mode Now on the Category drop down list, change it to Additional Dlls Now point it to the .dll you want to debug Hit Ok And now just hit F5 to beging your debug session