So, I've been playing around with Custom Challenges and I've come across yet another economy-breaking element, perhaps even worse than the first one I came across (Custom Campaign Challenges + ONI Target Locator Checkpoint).
You can bypass the daily cR limit.
To review, 343 Industries broke the in-game functionality of the daily cR limit when it attempted to raise it in early December. Since then, you still stop earning cR when you've earned 120,000 in a single day, just as you did before, only now the game will not tell you that you've hit the limit, it will still show post-game cR earnings (but not add them to your total), and it will not advance your commendations whatsoever as long as it behaves this way. Apparently, if you continue and earn enough of these "off-the-books" credits, you will reach a point (tens of thousands of cR later) where the game will finally give you the in-game message "Daily cR Limit Reached" and you re-gain the ability to advance commendations.
So, not only are players still capped as they were before, the game now behaves in these broken, confusing ways as a bonus.
On to using Custom Challenges to exceed the limit...
All that one must do in order to have their Custom Challenge credits not count towards the daily limit is to redeem them in-game on a date later than when they were awarded. I'll provide an example:
It's 6:00 p.m. local time. Over the course of 2.5 hours, you create and complete a series of Custom Challenges with a 3 hour limit that total 150,000 cR. You then shut off your Xbox 360. The last of your Custom Challenges will be awarded no later than 11:30 p.m. local time. When you turn your Xbox 360 back on and boot Halo: Reach at 12:01 a.m., local time, all 150,000 cR are added to your total and they DO NOT count towards your new current daily (broken) cR limit of 120,000 cR.
If you exceed the cR limit with a custom challenge on the current date, the game will actually award and then take back the cR. I created a new account to test these systems and had to laugh when I saw the progress bar move backwards after a game.
