Little Big Planet is essentially two different applications in one
1) An incredibly addictive and accessible platforming side-scroller
2) A powerful physics engine and game development system
The game starts out with a few simple levels which act as the introduction and tutorial for the game. The controls consist of the standard left stick for movement along with one button for "jump" and another for "grab" -- super easy, right? You play as a "Sackboy" which looks like a small hackie-sack with arms, legs and a zipper who must navigate through amazingly detailed levels. As you progress, you realize that the other buttons give your character even more personality as you can wave your arms, shake your butt, smile and frown, or even slap other "Sackboys" playing with you. Some of the movements respond to the Sony Dualshock Sixaxis motion sensor -- a very subtle but well executed touch. The first time I played, I got two others to hop into the game with me, and all three of us were immediately hooked.
While the initial levels are rather straightforward, it immediately becomes evident that the levels are designed to be played cooperatively which is necessary to unlock more advanced puzzles, but more importantly makes the game infinitely more fun. The simplicity of the controls makes it easy for anyone to join in and pick up the game without having to be a "hardcore" gamer, but the more advanced puzzles will offer a sufficient challenge for more seasoned gamers. The game supports up to 4 players simultaneously either through a single console, or played over the network. Another fun feature is decorating your Sackboy with stickers and decorations you unlock throughout the game to give your character a personalized look and feel. Each level has a very unique look and feel and incorporates different obstacles and challenges... and in some cases, vehicles which you must master in order to reach each end goal.
Of course, after playing for a while, you realize that the levels primarily serve as inspiration for the second main aspect of the game -- creating your own levels. Little Big Planet has an incredibly advanced game development kit to guide you through building your own levels. After watching a few tutorials, you can jump into building your own level using the items, decorations, and tools that you unlocked while playing through the original levels. The possibilities are truly endless as the physics engine at your disposal provides endless hours of tinkering. Once you've created your level, you can upload it to the Playstation Network to let others play it -- as well as test out creations from other gamers. After sampling just a few user created levels, it is really easy to see how much power these development tools wield.
This game really is an amazing accomplishment. Not only is the standard game fun to play, but it gives you the tools to create even more levels or try out any other creations online for free. The accessibility of the development tools allows anyone to be a game developer and immediately test out ideas on a live platform. This is the "must have" game for PS3.