Summary This is a classic Gamecube platformer that was entirely too unnoticed in its time, but is filled with tons of fun and replayability for gamers of all ages and skill levels.
Gameplay and Difficulty - 9 / 10 The main game (story mode) is dominated by a simple challenge: Navigate your monkey-in-a-ball over a series of suspended platforms (of increasing complexity) by 'tipping' the stage with your control stick so that your monkey eternally rolls downhill towards its goal. (akin to old wooden tilt-plane marble games)
It sounds simple, but it has a very natural learning curve which seemingly never ends so that you can keep playing (100+ levels!) and never stop being challenged right to the very end.
Eventually stages involve a lot of moving parts or puzzle-like challenges to solve before you can make it to the finish line, always within a 60 second time limit that keeps you on the move and challenging yourself. This is balanced with an 'infinite lives' replay model that allows you to fall of the edge or run out of time indefinitely until you figure out how to master a given stage.
Besides Story Mode, there is also Challenge Mode (easy, advanced, & expert difficulties) in which you do have a fixed number of lives and the levels truly ramp up to give even skillfull players a run for their money. Accomplishing each successive level of difficulty is rewarded with the chance to play unique levels not found elsewhere in the game.
The multi-player component of the game is a true winner. With many different styles of gameplay to choose from, you and your friends need never get bored with out-performing (or simply bashing) each other in these simple, but endlessly fun, minigames.
Presentation & Sound - 8/10 The game does not stress any graphical processor very much, but in a simple concentration / skill game, this is actually a blessing. The look is very simple, but at the same time polished and never oppressive. There are colorful backgrounds that actually do have quite a bit of character, but after playing for 5 minutes, you don't really notice them since every level has a new and exciting challenge that keeps your mind on the task at hand. The graphical richness rightly takes second fiddle to quality gameplay.
There is a simple soundtrack running in the back-ground of the main and party games that is pleasant and not overbearing (except when you are running out of time on the clock). Although not a selling point, it also is not unnecessarily distracting and allows you to focus on the task at hand.
Replay & Bonuses - 10/10 I've owned this game for over a year and I still haven't unlocked everything it has to offer... As you play the main game, you earn "Play Points" which are used to unlock a myriad of party games, and then other aspects of gameplay or 'gifts' like movies from the main story or extra lives to use in "challenge mode".
Given the ease with which one can pick up the controller and jump into gameplay makes this an excellent title to have in your collection for the days when you don't feel like doing 'serious' gaming and just want to relax and have some fast fun. I've never gotten bored with the challenges and particularly the multiplayer which is balanced so that an inexperienced player can pick up a controller and play against an experienced player without feeling overwhelmingly outdone.
The only games I own with equivalent replayability are Smash Brothers, Mario Party (X), and Warioware. (This is high praise, for those of you unfamiliar with the titles mentioned).
The Verdict - 9/10 Not to be missed. This game offers a surprising amount of depth to seasoned gaming veterans and yet a simple and accessible enough interface that your 8 year old niece can pick it up and start having fun in minutes.
Both the single player and multi-player modes are top notch productions that will have shelf-life far longer than most comparable games.