Buildings can be upgraded by using materials collected in scenes or as rewards when finishing scenes. Simply click or tap on the building to start the upgrade. A pop-up will appear and it will show you how many stars are needed until your building is fully upgraded.
There are two ways to upgrade a building:
- Click on “Buy All for xxx” using Cash. You may upgrade the entire building in one go, without needing to collect materials.
- Click on “Buy for” under each material. This allows you to upgrade the materials separately, one by one.
All buildings have 3 levels of upgrade but construction times vary from building to building.