Matt Soell dropped into our forum just to clarify one point: Combat Evolved was, in fact, a marketing catchphrase for Halo and not actually part of the title:

It's in all the printed materials and ads and press releases because the Marketing folks don't ever want someone who hasn't already bought the game to see the word Halo by itself. Nothing about that word screams running around with guns shooting people, and that bothered Marketing to virtually no end.

So there we have it. No word on whether or not Halo 2 would have a subtitle, though... hmm. Perhaps Halo 2: Blam! THAT at least screams running around with guns shooting people. At least, it does to us.