"Half-Life: Day One" This was the first official demo of Half-Life, including "The first day" playing time.
Half-Life: Day One is a demo of the computer game Half-Life. The demo contained the first fifth of the full game.
Half Life: Day One was designed exclusively for OEM partnership and was
often bundled with graphics cards. It was never available to the
general public. Half-Life's actual demo (available free to the general
public), Half-Life: Uplink, was released several months after Half
Life: Day One