Very nice game! I loved the art and the overall mood (even though it was a bit to dark in my opinion, I got lost pretty often due to the darkness).
I also loved the idea of a 3D typing game, there are some interesting mechanics that might come from it. For instance having some words to type flying around you, or using the perspective to trick the player.
As many others mentioned, it was difficult to get the hang of the controls. I feel like you do not need to control completely the camera with the mouse. It could be as a classic dungeon crawler where only 4 views are possible?
Anyway, overall very nice idea! (Obviously I did not get to the end of the 666 levels).