Game history buffs may remember Gearbox Software's Dreamcast port of Valve's classic Half-Life, which never saw the light of day. Well, now you can experience what was never meant to be, as this version of the game is newly available as a mod for those with a PC copy.
If you're truly a Half-Life nut, you'll definitely want to give this a go as it features improved graphics (see comparison images below), modified levels, new NPC models and props, difficulty tweaks (maybe even to that last infamous section), and a series of Dreamcast-related easter eggs. If nothing else, it gives you something to do while you grow old waiting for Black Mesa to come out.
Install Half-Life via Steam and hit the source to get playing.