I really like the idea, though I found it a little cumbersome in practice. The font you've used can make it difficult to distinguish which characters you need to type. You might also want to remove case sensitivity, or auto-capitalise player input. Being able to hold backspace to delete characters would also be helpful.
The other thing it could benefit from is a slower, more guided tutorial. The help page you have in-game didn't sufficiently explain the mechanics, at least for me.
With some more work, this could be quite neat!