Flashcards are a useful tool for learning foreign writing systems, but they are dull. Nichimoto Invaders makes it fun.
In Nichimoto Invaders, you can save the world from alien invaders while learning a foreign character set such as Ancient Greek or Japanese hiragana. Decrypt their defence systems by correctly identifying the key codes, and then you can shoot them out of the sky!
The game uses an intelligent teaching system which introduces new characters in a structured way and then ensures you know them by tracking your skill and retesting you at intervals.