PixelJunk Monsters is a tower-defense game in which players attempt to protect helpless villagers from hordes of marauding creatures by knocking down trees and building towers in their place. Gamers begin each of the 21 levels with a set amount of money to spend and a small number of towers available, but exploring the wilderness and killing monsters rewards players with money and crystals, which can be used to unlock more advanced towers. There are ten unique towers from which to choose, with the more expensive towers offering extra firepower or attacks specific to the nine different enemies. ~ Christopher Brown, All Game Guide