HALO 1 has a special place in my heart. I got to play it 6 months before launch as at the time I was working for Microsoft and was in charge of launching the then new XBOX in my state. (you have no idea how many legal documents I had to sign to have an XBOX and all launch titles at my house six months before launch
HALO 2 added the on-line multiplay that we had all been craving for. I did not play the single player campaign until years after the game released. It was all about the multiplayer ... Loved it!
HALO 3 had so much hype (and was given so many "questionable" review ratings of 9 - 10) that when I finally played the single player, I was very disappointed. It was a good game, but it was not the Earth shattering experience we were promise. Multi-player was still good, but due to the legions of "professional" style players now dominating the maps, new comers and casual players were turned off.
Only way for casual players to enjoy it was to just play with friends, but unfortunately for me all my friends hated HALO by this stage.
ODST did nothing to bring them back and was just an expansion pack in reality (or at least should only have been).
Reach looks promising and is now the only game on my "Must buy" list (so far
) for this coming Christmas period.