Ocean is an example of how simple an RPG can be and still be effective.
In Ocean, the players are all people who have woken up in an underwater Station with no memory of how they got there, who they are, or what the monsters are that are stalking and picking them off. They will try to solve three mysteries involving their situation, and survive to escape to safety.
The mechanics of the game are freeform with respect to everything except survival and mystery. Players develop the mystery through rolling dice to find clues to each of the mysteries (who are we? what are the monsters?) and to find supplies that will help them survive and escape. The supplies (weapons, keys, files, etc.) are described in detail.
As a LOST fan, I really like the "castaway" element of the game. The characters are isolated and must work together to succeed in a situation they don't understand. The deck is very much stacked against them mechanically - it's extremely unlikely that everyone will escape together. But with good planning and skillful play they may have a chance.
This competitive/challenge element is not something you normally see in narrative style games of this kind, and it works very well. It also sets up situations where one character might sacrifice themselves for the group, or might throw someone to the wolves (so to speak) for their own benefit, which are highly dramatic and interesting character actions not normally given mechanical weight.
This is a solid game that you will want to run more than once, to compare what was created across several groups. It's also an ideal convention scenario, with almost exactly enough content to learn and understand in a single session with a tight ending.
The presentation of the material with a comic book style to help people understand the tone and mechanics is also innovative and good (though the really constricted text gets a bit old at times.) Highly recommended.