Dead Rising: What actions / tasks are obligatory for finishing the game?

Question

I suppose, sit and wait for the whole 72 hours to pass isn't enough. Do PP are important? Do you have to solve all the cases?

Answer 1

Ending requirements

These are the requirments needed in 72 hour mode to unlock different endingd the farther in the letter goes the worst it is i.e. f=worst a= best

Ending A

Solve all cases, talk to Isabella at 10am, and return to the heleport at 12 pm on the 22nd

Ending B

Don't solve all cases and be at the heliport on time

Ending C

Solve all cases but do not talk to Isabella at 10am on the last day

Ending D

Be a prisoner of the special forces at 12 pm on the 22nd

Ending E

Dont be at the helliport and dont solve all cases

Ending F

Fail to collect all of Carlitos bombs on act 7-2

PP only is important if you want the achievement for it.  it wont effect the game in any way