Totally rent the game, and Totally purchase if at a low price.
The game can be relatively compared to Super monkey ball: banana blitz, however it remains different in certain aspects. First of all, you can't jump like in monkey ball, but you can tilt the whole level around in a 360 degrees motion, you will need this ability to complete some levels. As you would expect, you will control the ball by titling the wii remote. In fact, what you will be tilting are the levels and the ball will move accordingly. The game handles this aspect very well, and the remote is extremely responsive, even to the slightest movements. Having said that, you will need a steady hand to play this game as well as metallic nerves, because once you lose your temper its all over. The controls are solid and very simple, basically apart from titling the level, there is nothing else to do (apart from pausing and restarting). The game physics are solid, and ball will react differently to the different terrains in the level which makes things interesting. The gravity element in the game is also interesting, any surface has gravity basically, so its not like its always pulling objects downwards. If you hit a wall and tilted the remote 90 degrees towards the wall the direction of the gravity will change and the wall will become the ground, this will plays a significant role throughout the game and it is one of the things that distinguishes this game from similar ones. This feature will also allow you to pull off some ridiculous shortcuts, in some levels you can't help but try to take some shortcuts that might skip over 50% of the whole level (you will try endlessly by the way). However, in order to prevent you from cheating and finishing a single level in 5 seconds or so. You will have to collect a certain number of orange crystals, once you've collected all of them, you can go to the finishing line. There are also green crystals (one in each level) that are hidden or difficult to reach -some are hidden in some surprising places- and these will basically unlock few things so make sure to collect them all.
In terms of Graphics, while simple, it has a lot of charm to it. Even though most of the time you will be focusing on the ball only, but if you took a look at the background you will see some nice environments. The levels are well designed as well, and you will notice some interesting effect on the terrain. The game also has some nice particle effects that adds a nice touch to the whole feel of the game.
The game is well designed in general, and you the levels are designed in a clever way as well. You will run through different themes, such as a garden, sweets, and cityscape and others. All themes have different terrains, and style, and it adds a lot to the game's charm. As you progress through the game, you come across different unlockables, these are new levels, music soundtracks, secret levels and balls. Speaking of balls, there are twenty of them and each one of them has its own attributes and difficulty, there are certain levels that will really need the "Panda" ball to complete, because that ball is the easiest one ! The balls are cute and varied, you will most likely stick to a favorite as you progress through the game. Each ball has its unique sound effect, and they add a lot of personality to each ball.
The game's difficulty varies from one to another. If you have a steady hand and you know how to handle this game well, then most likely you won't be faced with any real challenge until the late stages of the game. However, having said that, even though the early levels won't pose much of a challenge they will be fun to play nonetheless. If you want to increase the amount of challenge you can do so by selecting a hard ball to control. There is split-screen multiplayer in the game, its basically a race to the end. The interesting bit is that you don't need two wii remotes to play multiplayer. Player 1 will hold the Wii remote and Player 2 will hold the nunchuk, this is good news for those who don't have two wii remotes. In addition, if you are a hardcore, and you're compeltely done with the game you can try something crazy like playing multiplayer on your own, because it is possible since you'll hold the wii remote and nunchuk, but I will have to say that its difficult and requires a lot of skill and multi-tasking, send me a video if you did so !!
Well, so far so good, but not until we get to the "value" aspect of the game. This is probably the only and definitely biggest problem in the game. Simply put, the game is very short for a fully priced game, you will probably finish the game in one to two sittings (depends on how good you are). Yes, these one or two sitting will be extremely fun, but then after that - apart from the multiplayer aspect- there isn't a lot to do apart from breaking your time records endlessly with no real incentives. Therefore, Kororinpa is a really fun game while it lasts.
As for the final verdict, I easily recommend it for rental since it is a short game, however, if the game went down in price, I can easily recommend it for purchase as well since the value increases significantly by the drop of the price.
I hope you found this review useful ! PEACE^^