Usually I am a fan to make the player experience more enjoyable that is why I tried to put a lot of stones around and increased the visibility in the dark. Your suggestion for the first level sound good! Initially the lights did not even had an healing/fire effect played when entering, was added quite to the end because I thought they lack feedback.
I would have downscoped a bit more and used that time in a proper level introduction and even better balancing instead of more levels.