Half-Life’s proper demo – Half-Life: Uplink, available free to the general public – was released several months after the full game.
Although sometimes marketed as such, Day One was never a demo version in the traditional sense, as the developers considered that at 250 MB it was it was too big to release on the Internet at the time and that it offered too much of the final game to be given away for free. Day One begins at the same point as the full game, but ends after the player completes the chapter 'We've Got Hostiles', at the end of the first day of the game's plot.
