Pretty good. Plenty of the items made sense in their placement and purpose but some were a bit illogical. The screws, for example, made no sense as to why they were inside the coin slot fountain unless somebody was playing a prank of some kind. The third gear having been either inside the wall that's broke down or was somehow wedged in the ceiling above the wall doesn't make sense. The crossbow's parts in general being so far apart don't make sense plus the fact that it apparently fires with no ammunition. Finally, the fact that a model of aether on the staff of Aristotle's statue is the key to the library is a bit silly in my opinion since it means that the curator(s) have to go through the same last tasks the protagonist went through just in case the curator(s) lose the actual key and wind up having to get the spare one from that statue. Asides from that, the puzzles were pretty good (especially the last one that requires knowledge of the classical four elements), the story is pretty good, and it certainly was fun to play. Nice job!