It's not solely based on luck... like a lot of gambling games it relies on you knowing something about probability and utility (how "worth it" something is). Just because you have a bad run doesn't mean it's rigged. Statistically speaking, some of you are going to get a lot of sucky rolls... too bad for you.
I think you'll find that the key in the door puzzle is a standard puzzle in a number of games. However, that isn't a negative comment. I loved the game and think it is awesome. 5/5
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