As a Japanese learner myself, I do take special interest in this type of game to see if it can be a viable supplement.
I could see it being a valuable Kanji learning tool, but it needs to expand a lot more in order to properly test its value. As a teaching tool, it needs to defeat and punish strategies that circumvent confident knowledge of Kanji. It felt very easy to cheat in the 'battle' step of the game.
The mechanic introduced late in this demo is called phrasing, but it was unclear to me how to specifically use it until I just mashed the phrase button. That said, once I did that, I saw what you were trying to pull off: a satisfying attack pattern.
Particles are easy to understand at first, but become very difficult as you expand their types and usages. For example, は (pronounced わ) is the marked topic of a sentence, but is often chopped off when the topic is obvious (わたしは or あなたは). が、に、と、とき、から、まで、を、も is a library of many more particles. When phrasing, particles would do well as attack coordinators while the separate Kanji words serve as foot soldiers.
There is a lot more to learn about how the Japanese language works and how Kanji works, and I implore you to continue your Japanese study. I am using みんなの日本語 and will be starting Lesson 34/50 soon.