This is a cool idea. What if the challenges varied based on the powers of the idols? So in order to prove yourself "worthy" of the long life idol, you have to survive the deathmatch (this should be the first movie), but in order to get the wealth idol, you're stripped of all your belongings and thrown alone into the jungle to see how long you last. You could even do some fun Twilight Zone-style endings, like maybe the winner of the fame idol had to kill a ton of people to get it, and he/she becomes infamous across the world for their murder spree.

Maybe in the last movie, someone decides that they want all the idols so they engineer a massive mashup game with all the previous winners (and themselves) that they've rigged, and the other winners have to team up to stop him/her.