I have been trying to get the Monopolized achievement for quite some time now. I have completed every level in Halo 2 on legendary in under 24 minutes EXCEPT Gravemind, which the leaderboards says I have completed in 38 minutes. Originally, I did complete this mission in 38 minutes. Since that first attempt, however, I have completed Gravemind in 32 minutes, which would give me the achievement. But, the leaderboards do not show this new time.
When I achieved 32 minutes, I would save and quit whenever I died in order to reset my time to when I first got the checkpoint. Does this void leaderboard completion times? If so, I guess I need to do the mission more legit… but dang, that mission is HARD!