I like the concept a lot! I think it's really cool and interesting ^^
My main problem while playing was that I have an azerty keyboard so the controls were very unnatural to me and got kinda tedious because I kept forgetting which key was what, so I have to admit that I haven't finished the game yet (I do plan to try again when I have more time tho).
Also the first time I played level one I got confused because writing "heart" seemed too obvious and I didn't understood properly what I was supposed to do (but that might just be me, haha!) so I tried to write "rat" and nothing happened... And then I read the description and finally got it xD
Overall I liked it, I found the the music to be nice and fitting, too, What I saw of the story (I gave up after level 3) seemed sweet!
(EDIT: correcting english mistakes, don't mind me)