Ok, here is my simple description of LittleBigPlanet:
The game is basically a platformer.
You move through levels controlling a sackboy avoiding drops and other dangers (like lava and fire) avoiding enemies and solving puzzles to progress.
There is a single player mode (rumored to have up to 25 levels), created by the devs. You can play through the single player in co-op with up to four players.
The other side of the game however, the side that has a lot of people talking, is the creative side. You are free to create levels on your own (or with others) for your own entertainment. The creative tools are extremely wide-ranged, varied and impressive. If you so please, you can then upload your level so that others can play and rate it online.
Your Sackboy has the ability to slap other players, has a mixture of emotions ranging from sadness to anger and is also highly customisable.
That about sums it up.
