This game teaches you to read words.
You can use it to expand your vocabulary, and learn how to pronounce kanji in various contexts
Although some of the simpler kanji are words in their own right, most words consist of two or three symbols in combination, sometimes more.
The game uses the honour system to track if you got the answer correct or not. It shows you a question, and you just press the appropriate button to indicate if you knew it. This is a lot faster than having to type, so you can rattle through revision in less time.
It also allows you to test yourself with various degrees of flexibility. So perhaps to begin with, you're just trying to remember the English translation, without bothering too much about the Japanese reading. But then as you get better, you can get more strict on yourself.