Black Mesa: Uplink is the recreation of the Half-Life demo (HL: Uplink) released by Valve in early 1999 with featured content that was scrapped from the original storyline.
The release version of Black Mesa: Uplink (version 1.0) - Installer EXE version.
To play Black Mesa: Uplink, you will need to have an installed version of Black Mesa on your Steam account. You can download Black Mesa here.
Note that the installer version overwrites Black Mesa files. It will however not directly affect your experience of Black Mesa. Original Black Mesa files can be restored by use of the Restore batch tool included in this package. If you don't want to overwrite any files, I suggest you download the ZIP version instead.