You start out as a Slime named Rocket living in the peaceful village/town(I'm not really sure...They seem to portray it as an island)named Slimenia. What seems to be a peaceful day turns out ugly(Like you didn't expect that) when a group called "Plob" for no reason decide to destroy your village and capture all the slimes. While this is happening, Rocket and his friends are playing in the Palace garden with a special flute but a guard sees them and he swallows the thing whole. So, when the Plob start kidnapping everyone, they find Rocket. Luckily, Rocket appears to be a baseball bat so they chuck him away.
You find out that the Plob have stolen the 100 villagers from your town and it is your duty to find and rescue them all.
After you reach the second area you find out that the flute you have can summon a gigantic tank that can own all. So, you can fight monsters by using your tank(Only if they have one. There are maps where you can find monsters with tanks) and during parts of the storyline, it will be needed. The ammo you get can be obtained from Tank Battles, Alchemy, from rescued slimes(They send you a letter thanking you and attached is an item you can use for your tank ammo) and in the environment. There are many more tank features such as increasing HP and allowing crew members to help you(Slimes and monsters).
During the course of the game, you unlock extra areas depending on the amount of slimes you have found and some slimes even allow you to do things(Paint, HP increase for tank, etc.) which makes collecting slimes both important and like a treasure hunt.
You only get a few moves during the game.
Electoblast: You hold down A and stretch out with the D-pad. Depending on how long you stretch and how long you hold the button for will determine the strength.
Master Blast: Just an upgraded form of the Electoblast. Allows you to destroy ice blocks.
Rollerblast: Roll down a hill and crush everything in your path. Allows you to destroy piggy banks as well.
Throwing: Press 'B' when holding onto an item/monster and you will throw it into an enemy.
Slash: When you obtain a "Toy Slime" soldier doll, you can press 'Y' and it will slash things for you.
Hover: Press 'A' to jump then 'A' again to hover for a couple seconds.

Storyline

I found that it needed a bit more in-depth about Slimenia and how the Plob's came into being, but other than that, it was nice and easy to follow.
Rating: 7.5/10

Gameplay

Great, fast-paced and really fun.
Smashing into monsters and throwing them around is great fun. Shooting yourself across bungee cords in mid-air is fun as well.
I would have liked to see a couple more moves though, like a ground-pound or a hover-through-the-air type of thing.
Rating: 8.0/10

Mini-games

I've only seen one mini-game and that would be the Tank tournament where you battle it out to see if you can get to the top with your tank.
I would have liked to see many more mini-games but what can you do?
Rating: 7.5/10

Appeal

I found what appeals to me are the different monsters and slimes, but the most appealing to me would be the Tank battles. They're really fast and you need to collect things to make your tank and artillery much more powerful. The crews make everything a whole lot easier but can be a pain at times.
Rating: 9.0/10

Overall

This game is great for all ages and has a special kind of appeal to it.
Also, even after you beat the game, there will still be many more items to get, 100 slime completion, 5 obtainable tanks from the Tank minigame and Church, monster collection and monster recruiting for your team and more.
Even though it may seem like a children's game, it's really fun and can keep you addicted for a good couple days trying to get all the items, monsters, crew members and slimes