Buildings and Event buildings have Ranks, which increase as you beat levels.
Each successful research you complete increases the Rank progress %. When it reaches 100%, the Rank of the location or mini-game increases.
There are a total of 8 Ranks:
I - Stonemason,
II - Builder,
III - Adept,
IV - Master,
V - Engineer,
VI - Expert,
VII - Creator,
VIII - Originator.
The Rank number you need to reach is displayed in the Location Entrance window.
As the Rank increases, so do:
- the Energy cost and the number of items required to enter the location,
- the number of items you can find inside,
- the rewards for research.
Also, the variety of Chargers and collection items you can obtain changes with each Rank.