VERC (HL2)

Interlopers.net Tutorials (HL2)

Fortress Forever MOD (HL2)

Wavelength (HL2)

Source SDK Docs (HL2)

TFC Entities (HL1)

Half-Life Entities (HL1)

TFMapped Tuts (HL1)

D.O.E. Tuts (HL1)

Compile Errors (HL1)