This is the best game I've ever played, and I've played a lot!
Now to the good news. I'll start off with Classic Mode. What happens in this mode is that you play off against multiple cps one after another. There are also 3 'challenges' in the middle of all of this. The first is 'Break the Targets'. Each character has a specific area design for this. What you do is hop around breaking all of the targets. The second is 'Grab the Trophies'. What you basiclly do is knock the trophies into a base with your attacks. The third is 'Race to the Finsh'. You basiclly race to the finish. Then comes the hard part, Master Hand. He's the boss of Classic Mode and can also be accompanied be Crazy Hand. These 2 are a force to be feared when they work together.
Now is Adventure Mode. You do the samething as in the other modes except you have to complete a task while doing it. Like in the Link stage, you go through a maze trying to find the Triforce symbol. Along the way there are enemies you can fight. At the end you battle either Giant Bowser of Giga Bowser depending what difficulty you set the mode on.
There is also another main part of the game. The trophies. You will find them in the modes you play on in the game. Once you get a trophy, it shows you a picture of it and has info about it. There are hundreds of them. Try to collect them all!
There are still more things, but I won't tell you about them, it'll spoil the game! Overall this game is amazing and fun, probably the best ever made! Try it, it's worth it.