In Dreamcast news that can only be described as somewhat odd the unreleased Dreamcast version of Half-Life has been released for the PC.
It's a bit interesting, I thought the only major differences were from the High Definition pack which was already available for the PC version. However, the creators of this mod state that there are many other differences including additional graphics, NPC models and Dreamcast easter eggs in the game.
Personally I only noticed one little extra thing when I played the Dreamcast version but it did run very nicely.
More info here:
If you have the Steam version of Half Life you can run the Dreamcast version as a mod.