you getting try of the way Halo Pc play and like to see it in anew way. found a great url-site were they have all types of mod for it and mod makers toboot there were the member all chip in to make up new mods for the game.
have a look:
"halomods.com"
some made new monsters to fight and new charters for the game Halo Pc they have other type Halo there too.
one of it member and his group are making anew levels and charters for the game too. HaloPc