This was actually a really difficult thing for me to decide. Seriously, I was getting nervous that I wasn't going to be able to post at all...
But I finally decided on Tak and the Power of Juju. This is a Playstation 2 game, and it takes place in an ancient world without technology. The pupanunu people worship the moon goddess, whose power is contained within three magic moonstones housed in the hut of the head shaman. Tlaloc, an evil shaman who was passed over for head shaman, decides to take his revenge and steal the moonstones so he can destroy (or control, I forget which) the moon goddess and her power. Prophecies foretold of these happenings, and of the one that would save them: a warrior trained in battle that will relieve Tlaloc of the moonstones and save everyone.
There's just one problem: the mighty warrior, along with everyone else in the tribe (save the head shaman and you/Tak) have been turned into sheep. Needless to say, that's not supposed to happen. The mighty warrior is supposed to be immune from livestock transformations, so right from the start, the player knows something isn't right here.
Yeah, this game has humor out the wazoo, and it's really creative the way it's set up. Along with the moon goddess, the tribe worship Juju: spirits with special abilities. At the very beginning of the game, the head shaman is trying to conjure one, and then spots the player in a "magic box" with a strange stick in his/her hand (lol!). The player is a Juju, basically, and is called upon to help Tak save the tribe and defeat Tlaloc. Eventually, it's revealed that Tak is, in fact, the mighty warrior of prophecy, not the oaf that the head shaman trained.
But screw that! I want to be there in place of Tak! The adventure is really cool, and the world is gorgeous. The graphics aren't great, but the colors are stellar, and the characters Tak meets along the way are both hilarious and awesome. There's one island where the people worship chickens (yeah...they do), there are helpful animals all over the place, and some of the magical abilities that Tak acquires throughout the game are really cool. Tak also gets to talk to the dead a couple times, and lead some mummies through their domain so he can open up a gate into the spirit realm. I actually haven't beaten this game yet (Tlaloc's an asshole), but maybe if *I* were in there instead of Tak, I would do a better job =P