Paranoia is a pen & paper role playing game. It's set in the distant future in a society driven underground (into a placed called the Alpha Complex) by a "Big Oops" and controlled by a totally insane, broken AI ("The Computer"). It's one of the few RPGs that are comedic by intent. It also has you looking over your shoulder and watching everything you say. It is an absolute blast to play - I haven't been able to play again since we can't gather enough interested players, but the one occasion I did I got cramps from laughing so much.
The rulebook is apparently a very fun read, though I'm not allowed to read it because having knowledge of the rules is actually illegal and can result in termination of your character. But that's OK, you get 5 more - people come in 6-packs, "because 6-packs make people happy." It makes the gameplay much more fun - you're more likely to take stupid risks and not feel too bad about killing NPCs. Your name is ended with the number of your current clone: Puggles-3 would have died three times, for example.
Players usually play the Computer's troubleshooters - people whose job is to "find trouble - and shoot it." You are typically given a mission by The Computer and have to complete it. At any time the Computer may forget it assigned the mission, or change the requirements (possibly without notifying you) or may give you a conflicting mission to complete at the same time. It may give you missions that are impossible for you to complete because of your security level. In addition to that, most players belong to a secret society and/or are mutants with a special ability that they must hide from The Computer and their teammates. The Computer is deeply paranoid about communists, mutants, The Outside, and secret societies.
When we played, there was no out-of-character chat allowed - everything you said was "in-game" except when the GM said it wasn't. Simple statements like "I'm getting a drink" would probably be fine, but complaining about The Computer or mentioning your secret society could get you in trouble. (It took one of our players a little too long to figure that out)
The security clearance system is based on colors - you can touch/use/be in areas that are your color or "lower," and you get in trouble for being in areas/using things that are higher that your clearance. The ranking system goes (low to high):
Your jumpsuit is the color of your security clearance. Your weapons are lasers that can only kill those of equal level and below. Luckily you can find items of clearances higher than yours - higher clearance weapons, jumpsuits and - if you're really lucky - paint. Of course if the Computer catches you with a clearance it doesn't remember granting you, can expect some issues.
The clearance system leads to some interesting situations. Say you're orange clearance and you enter a room via an orange door. The room is orange so you enter. When you turn to leave, the back of the door is painted blue - you do not have the clearance to exit. You can try to find another way out, or you can take your chances with the door. I seem to recall one of our players being given the task of painting a hallway a color that was higher than their clearance.
I was a Hygiene Officer, which means I had authorization to strip any random person and clean them (though it was a good idea to avoid cleaning people with higher clearance...). I could also clean up crime scenes - be they my own or not. My name was Kthxbai and The Computer called me "thinks-B". The Computer liked me because I never misbehaved when it was looking and sometimes I gave it complements.
We had a Loyalty Officer with us - they are authorized to give random "loyalty" tests. The loyalty tests are hard -
How much do you love The Computer?
a) a lot
b) very much
b) a large amount
c) a duck
and no- it's not a mistake that "b" is repeated twice.
We also had a happiness Officer (authorized to distribute drugs to improve morale) and an Equipment Guy (robots/hacking/repairs). I actually don't remember what our mission was - probably because it was that convoluted/vague. Also it was a year ago.
All I know is that it's one of the most fun game I've played* and I want to play again.
* we had a hilarious campaign of Call of Cthulhu one time. In a library, weaponless, I wanted to grab a hardcover book to chuck for nonlethal damage. Roll for search check - 1. "You fail to find a book in a library..."
The whole damn game played like that.