Thanks. Very interesting indeed. This is the first comment so far on this topic that seems to have a chance of providing logical evidence against the viability of the game.

[EDIT] AFAICT, the mangled world hypothesis also suffers from the mathematical ugliness issues as the single world interpretation: nonlinear, nonlocal discontinuous action. Of course, you can assume that for the sake of eliminating quantum roulette type scenarios, but it makes the theory much uglier.