You have to save princess from this evil world. In this world, there are different types of monsters and traps, so be careful. Also a lot of places are there with hidden treasure.
Game is available at http://harshjain.me/Adventure-Time
Princess is in the middle of map, so keep looking.
Princess is locked in a castle and you have of find its switch. The switch is in another castle, and route to this castle is through a cave. Then press switch and gate of castle will open. Go back to original castle and you will find princess there.