The main purpose of this modification is to add Portal Gun from one of the best puzzle game's, called Portal. You will be able to play the whole Half-Life: Source single-player campaign with Portal Gun. All feature's from Portal work's great in Half-Life: Source.
How To Install.
You need to have Half-Life 2 and Source SDK Base 2007 installed in Steam.
Then download "hl1_portal.rar" archive in provided above link.
Once it finished downloading, open this "hl1_portal.rar" archive with WinRAR or 7-Zip program.
You will see "hl1_portal" folder in this "hl1_portal.rar" archive.
Extract it to your "sourcemods" directory.
Then change your language in Steam to English.
Quit and restart Steam.
You will see "Half-Life: Source - Portal Edition" in your Library.
Left click on green "PLAY" button.