Just came out a couple of days ago. :D
The premise is simple, you're a 4 inch(10 centimetre) tall robot, whose purpose is to maintain parks all around the world. You as, one of millions of Chibi-Robos get sent to a desolate park that hasn't had visitors in month. Your task task is to restore the park to it's former glory. To start with, all you've got to work with is a radio, a water sprayer and a few buds. You must water these buds to turn them into flowers. If the flowers are white, you will be able to dance to the beat of your radio is order make the flowers happy. When this happens, the flowers will send out more buds and you must repeat the process. Areas will become grassy when you've planted enough flowers. You'll be rewarded with happy points, which are turned into watts... which serve as the currency of the game. You also need watts to keep Chibi-Robo running.
Luckily, you have many allies throughout your mission. Ranging from soft drink mascot penguins, to a French puppet, even a monkey with a green afro. You will also return to your Chibi-House when you're running low on energy, you'll talk to a pink mechanical snake thingy named 'Chet'. He basically functions as your guide, giving you tips on all manner of things. His dialogue is bloody annoying, since he repeats the exact same lines everytime you speak with him. This is my only real gripe with the game thus far.
About an hour in, you'll be introduced to the smoglings, unpleasant little black things that run around turning you flowers into useless black flowers that wither at the end of a day.
Anyway, I'm a couple of hours in at the moment. I've got 154 flowers, and 4100 watts in reserve. Good fun.