Currently, in order to get a combo achievement (500x, 750x, 1000x, 2000x), you have to achieve the combo AND set a new personal best. Is there a reason for this? Especially for the 2000x combo, it makes it a big disadvantage for users who have already played through the marathons and want to get the achievement on easy/halftime, but can't because their current score is already too high. It's almost like you don't WANT to do decent on the marathons because you want a low enough score that you can beat with easy or halftime on...