Capcom Vancouver did it, guys. They did the one thing that would get me interested enough to buy Dead Rising 2: Off the Record -- put in a mode free of time restraints. This is being called -- wait for it -- Sandbox Mode.
In addition to being selectable from the start, Sandbox Mode supports single-player and co-op. Also included are challenges complete with online leaderboards. Some of the examples given were "Rumble in the Jungle," "Chop Suey," and "Silver Strip Smackdown." Better yet, you'll earn in-game cash for completing these.
As someone who legitimately enjoyed Dead Rising 2's competitive multiplayer, this all sounds terrific.