I'd like to see you come into halo, play for a month, and have a positive KD. Doubt you would
ANYONE CAN DO THAT! You can have 100 deaths and 1 kill and it's still positive (not possible to hit negatives). Nice try though!
not to get into an argument here, but i wouldn't want to beat a game in 15 minutes... that's not fun at all.
The point is the amount of replay value there is. You can go for a straight speedrun and try to get the lowest time possible (like this guy), you can play through normal, you can tyson run (using melee only), you can go for max speed runs (100% of map complete). Unlike new single-player games where it's just a boring rail shooter that holds your hand and has cut scenes every 2mins with absolutely no replay value.