I've also begun work on a mechanic that deals with the hidden immunity idol that will have it's own sort of mini-mindgame of it's own.
Each player may once during the dayphase of the game (before or after the immunity challenge) go out and look for the immunity idol. Before the night, I'll let them know if they've found it or not. For sake of the example, we'll say their chances of finding it are at 50% and failure at 50%.
Now, for everyother person from the tribe that goes out and looks, the chances of them finding it goes down.
So if Player A and Player B go and look, instead of a 50% chance of them finding it, it's 25% chance each. There would still be a 50% chance of failur for both parties.
However, since there is only one HII per tribe, once it's been found the chance of all future searches drop to a 100% failure until it's returned.
This does need to be tweaked with exact starting percentages for fail/find, how many chances a player gets to search, if they get more chances when the tribes combine, whether to variable the system based on the number of searches conducted previously, etc. I'm open for suggestions, if this even is a system people want to use.