Well, i was pretty lost after collecting the first items. Theoretically all your ideas are correct. But some more hints would be cool (maybe just optionally to leave the challenge to the hardcore gamers). Or simply make the hotspots visible. After knowing what the player can use, it will be easier to figure out everything. As it is now, it's hard to find out where the items can be placed and what is just background.
For the rating: everything works, no bugs found but a bit short
4/5