The goal of Merge Mansion is to help Maddie restore Grandma's mansion and uncover its many mysteries. To do so you need to merge items on the Merge Board located in Grandma’s garage to create higher level items and discover new items that can be used to complete renovation tasks around the mansion and its surroundings.
Merge high-level items and complete tasks to earn experience points (XP) to help you reach new player levels. In doing so, you’ll earn special Chests as rewards as you renovate Grandma’s mansion. 
Happy merging!