Half-Life: Uplink

Half Life: Uplink was a Half Life demo released in 1999. The level featured in the demo does not actually appear in the full game.
 PC

Overview

Released in 1999, Half life: Uplink is a demo for the original Half-Life. The level featured in the demo does not appear in the full game, but is cut content that was decided to be released as a demo. The demo starts just before the resonance cascade. The "plot" of the demo is that you have to go and tune the radio satellite so it can sync up with a satellite so that the people at Black Mesa can contact the outside world so that people would know what is going on at Black Mesa. Uplink was included with the Game of the Year Edition of Half-Life as a mod, and was included with all subsequent releases.