This is a rather simple tower defense game but it does offer some challenge, at least on the toughest of the three difficulty levels. You have to survive 50 waves of zombies so make sure you are ready.

Build and upgrade towers so that the zombies cannot make it through the maze to escape from the end. You need to stop 50 waves of zombies before 20 zombies escape.

You earn interest on your earning at the beginning of each round. It is therefore best if you wait to build or upgrade a tower until after the interest is applied, if you can.