The objective of the game is to build walls around your wizard to protect him from the ogres' attack. You have to click on them to zap them. When an ogre touches a wall, it vaporizes. When you play it in Wimpy Wonderland Island, you can enable easy mode by clicking on the wizard at the beginning. However, if you do so when you are playing the game elsewhere, it'll just say that you haven't enabled cheats yet and you will not be able to unlock easy mode.
Though it wasn't necessary to play this game to complete Wimpy Wonderland Island at first, the island was later changed so that you will have to beat this game to proceed forward.