"The 35 puzzle safes that you encounter are quite challenging and at times hair-pullingly difficult. Some require you to decode a certain phrase, while others involve deciphering a pattern. Some safes are connected, in that you need to solve one to obtain the key or password to unlock another. At times solving a puzzle requires some outside knowledge, such as knowing the rules to some obscure sport or game, which I don't think is fair. Depending on how good you are in solving puzzles (or how often you cheat and Google the solutions!), it can take you from a few hours to perhaps even a few days to finish the game."