I'm not sure how I'll theme this, but I have a strange co-op idea. (Well, it starts as a co-op, anyway...)
I think the players are on a mission to Mars, maybe, and one of them is infected with a disease.
Each player has two(!) identity cards, one visible only to themselves, and one hidden to everyone.
The card visible to the player states what that player knows, like "Feeling well, nothing seems wrong" or "Coughing a lot, don't feel very well at all" These cards might have numerical values or something to make their condition more clear.
The second card states their exact condition. "Infected", "Immune", or "Vulnerable".
At start, no player knows whether or not they are infected.
During play, all of the players goal is to survive as long as possible.
The only way to find out whether or not you are infected is to have another player test you. And then that player tells you what your condition is. That doesn't mean they have to tell the truth, though...
I need some help on some obvious holes in this game.
A) How does the disease spread?
I have no clue here. I am a dice fanatic but realize that this is a bluffing game and not one that should be left to chance. Also, if the spread mechanic relates to specific players it gives away who is infected.
B) What does the disease do?
It could incur a penalty on players to make them easier to spot, for example Person 1 hasn't done this action; I think he is infected. At some point it should eliminate players. I like the idea of a way to keep players involved after death somehow.
C) What do the players do?
There must be a voting mechanic, like Mafia, to eliminate players who are suspected to be infected (rhyme!). There must be a way for a player to analyze another player, and then potentially lie about it. If there was a group player action system, that would make disease spread easier, ex. Person A has been spending a lot of time with Person B, if either of them were infected they both are now. Maybe each player has the ability to give each other player a card with an infection value on it- even if the player giving the card isn't infected with the disease?
I'd love advice and criticism on this idea.
There also has to be some way to link the two identity cards. If one says "Feeling really bad." and the identity says "Immune" then it won't work. Or vice versa, someone Infected drawing a "Feeling great" card. Forgot about that.