Adventure at the Château d'Or

Relevance:
*) mirror balls -- No connection to the game world, and no logic to the
   solution. Just exhaustively place each ball until it lights up, and when
   all are placed you get a clue.
*) Paris homework -- "The Duke's a big fan" is just a cheesy cop-out.

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Real-time:
*) dungeon -- You get there without warning, and can't save once you're there.
   If you don't make it out (and you can't, because of a bug), you had better
   have a convenient save game or you're stuck replaying. Fortunately, all
   you need from there is information. I didn't even have enough time to read
   the note within the time limit.
*) Duke's steam image -- Not timed, but you must pay attention to sound.

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Reasonability:
*) vases - A combination lock that you have to solve by trial and error.
*) drinking wine -- 7 times!! With no indication that you would want to.

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Difficulty:
*) Paris exam -- Taking the "edu" in "edutainment" to heart.
*) Duke's steam image -- A different sort of twiddle puzzle.
*) spray painting -- Not really that hard, but at least it requires deduction.