Instructions
Play through each of the story levels. You can access them by going through the doors in the hub world. After finishing a level, a yellow arrow appears over the door in the hub. This indicates access to a treasure level.
Enter a door with a yellow arrow above it to start a treasure level. You will play through the level with the two characters in your control when you step through the door. After entering the door, a message will pop up telling you which two types of characters you will need. Exit the level via the pause menu and select two characters of this type. For example, a character with a gun or a character with explosives. The characters can be found wandering the hub. Return to the level to continue the treasure level.
Proceed through the path set in front of you by the set up of the treasure level. You will need to complete tasks to make the treasure chest appear. These tasks include shooting targets, destroying enemies, popping balloons with vehicles, creating objects to hold down buttons, or destroying environmental hazards. Use the characters indicated by the level and stay on the path. Destroy everything you can and build any LEGO objects presented to you. Do this in all of the treasure levels to unlock every treasure chest.