What is the Finger Addition 1 game, how does it work?

According to the introduction of Denting the Universe, Finger Addition 1 is a Educational game on the Android platform. There is currently a 1.0.0 version released on Mar 09, 2019, you can see the details below.

This app is meant for young children to get ready for math before they start school. Budding mathematicians need to understand numbers as the first step of the journey into math. Our hands and fingers serve as very good tools for counting and adding. This Finger Addition app is an excellent first step for young children to count and add with the help of their hands. The levels start as very easy, with just one hand counting, and progress slowly to two hands. Children should feel very comfortable in one level before moving onto the next levels. The simple app design is perfect for very young children, so they are not distracted as they enjoy learning and practicing their numbers. Recommended age: 2 - 5 year old children.