Great job on your first level! I enjoyed it. It's a calming, relaxing little hide-and-seek challenge that was fun and rewarding.
This is definitely [Scenic/Normal/Medium]. You can't call this environmental because it has enemies. You could EASILY make this environmental, which I might recommend, since all of the difficulty/cleverness comes from the hunt, and it is a very aesthetically pleasing level otherwise. If you decide to go that route, you would need to take out the enemies and add in a -touch- bit more ambiance in terms of scenic detail.
Gave you a :hiddenstar: for making a level I would play again. :)
I must've spent 10 minutes looking for that damn purple key, and it was right there! Good job with hiding them!