The game is based off the popular anime by the same name. Yoh Asakura is known as a shaman. Someone who can communicate with spirits. A spirit named Amidamaru joins Yoh on a journey to become the Shaman King, an event that only happens every 500 years. You play as Yoh and travel on the journey with your friends and spirits to stop Magister's evil plan to bring back Mephias (an ancient Shaman King) and take over the world.
To get to each level you follow a path. The paths go in different directions and you have to complete a level to get further along the paths. You can go back and redo levels if you wish, but you have to follow the path so if you want to complete a level you did a while back you have to complete the levels in between to get there which can be rather annoying. Sometimes you only have one choice of what level is next and other times you will have two or even three choices.
The game is a side-scrolling adventure. In each level there are various creatures to fight and platforms to jump to and you must make your way from one side to the other. Some creatures are harder to defeat than others, but most are rather easy. As you go along you collect spirits/guardian ghosts which you can then select as your main spirits to help you defeat enemies.
You can also pick up various items or buy them. For example, a hamburger can be bought for 1000 yen and will increase your health by 120.
The controls are simple, although having said that fight and jump felt the wrong way round to me, but perhaps that's through years of playing Playstation games where those moves are usually the opposite way round. Still there's nothing more annoying than accidentally trying to fight thin air instead of jumping and ending up dying from falling off a platform. There are special moves which you use the R and L buttons for. You can assign spirits to these two buttons and they allow you to do different, more powerful attacks. You are limited to how many times you can do special attacks though.
The audio varies between levels but it is rather repetitive. There is always the option to turn the volume down/off though.
The characters all look as they do in the show. The background is simple (sky and grass) but it looks fine and there's nothing to distract you. The graphics aren't anything special, but they're good enough and as good as any other Gameboy Advance game.
This game varies quite a bit in price. Recently I've seen it selling for around £50, but at the time of writing this it is selling from about £15 and before the random price rise it was roughly this price. While it's a fairly easy game to find the number of people selling it is limited which is often reflected in the price.
Shaman King is a good game overall. It probably helps if you like Shaman King as otherwise you may find it a bit boring at times, but if you like side-scrolling adventures this is worth playing. Recommended.