After the villagers build all sixteen monuments an intermission sequence will begin and a new level will start. Fulfill the villagers wishes and the credits will start after they build their monument. Several bonus levels will now be unlocked at the main menu.
To unlock the secret Mystery Monument you have to build the LOVE and HATE versions of the first 15 monuments.
All the monuments do not have to be built at once but it must be on the same saved game. Once they are unlocked in the Monument Museum destroy one of the existing monuments and the Mystery monument will be built.
This will trigger a cut-scene and unlock the bonus maps and alien level
