Eh, nice ideas (liked the vast cave with waterfalls best of all) and OK for a first level, but too many bugs. First screen, there's a rock adjacent to the right side of the screen, and no corresponding rock on the other side = instant wallswim when jumping back. Screen with the grey bouncer, the bouncer doesn't bounce and produces an irritating noise - you probably placed it inside layer 3 or something. Some wrong layers here and there (some mushrooms on layer 3 instead of being in the background, etc.) and so on. Also, you should rename the knytt.bin file to "Casey - In a dark cave.knytt.bin", so that people won't have to spend time looking for where your level is in their KS directory.