Alright, so I'm guessing you're familiar with the concept of Prisoners' Dilemma. Two prisoners are given the option to either turn their friend in (say they're GUILTY), or to not (say they're INNOCENT).
If they both say the other is innocent, they each get a 2 year sentence.
If they both say the other is guilty, they each get a 4 year sentence.
If one says the other is innocent, but the other says he's guilty; the one who was dobbed in gets 6 years while the other gets his sentence dismissed completely.
Of course, that's if there are only two prisoners.
For this game, the police have caught four criminals. And each are given the offer for each other individual. They can turn everyone in hoping they don't do the same, or they can dob in the one they hate and then be nice to their other two friends.
The catch is that the police here are really keen on seeing people in jail. So let's say Trev and Ali turned Dave in, but Clint didn't; they'd give Clint an extra 4 years for lying, because clearly Dave was involved.
When the game begins you will have 48 hours to message the other prisoners, privately or publicly, and see whether or not you want to dob them in or say they're clean. When I post all plotting must cease, and you will then have the first court case. You will see who turned who in, and then must again testify for the second part of the trial. But for the second part of the trial, there is no communication. You either stick to your plan, or get the little bastard who went back on his word. You then participate in part three of the trial, and at the end of the day whoever has the least amount of years to be spent in prison wins.