I'm not a huge gamer, but I LOVE this game! The plot is completely absurd, but that is part of the charm. And the actual play format is so simple, anyone can learn and catch on very quickly. Its simplicity is part of what makes the game so addicting!
Basically you are a little alien-type creature who's father happens to be the slightly insane King of All Cosmos. The King was bored one day and decided to break all the stars. The people of the universe didn't like that very much, so he decided to ask you, his tiny son, to create new stars by rolling up various objects into a katamari-ball and launching them into the sky. You start small with thumbtacks and paperclips, and work your way up to animals, people, cars, buildings, whole islands, etc! It's crazy and sooooooooo much fun. To top it off, the soundtrack is just as wacky as this game, but it is completely and utterly catchy. You will find the songs getting stuck in your head at random times of the day, even when you aren't playing.