Add One is inspired by an exercise in Daniel Kahneman's book Thinking, Fast and Slow.
The principle of the exercise is simple: First you read four individual digits, you have to remember them and increase each individual digit by one.

Currently there is only one static game mode. Four randomly generated digits are displayed one second apart. After a short pause, you have to enter the digits increased by one again at intervals of one second.

There are still many expansions planned for the game.
For example:
* Configure pause time
* Change the number of digits
* Change how much you have to increase each digit (+3 instead of +1)