Thanks for the feedback!
I was myself quite concerned about the gameplay being boring at some time, but I couldn't come up with anything else in the short time I had. Also in each room you'll find a single key, meaning that if you're missing a single key, you'll only be able to find it in its respective room and nowhere else. Although I must say finding all the keys can be very easy just as it can be very hard, as everything is based purely on luck.