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There is a difference between challenging and tedious.

This game starts being challenging, and ends being tedious. Almost all puzzles can be saved and being rated as challenging, but for the Clock one and the Work = Life ones are just pure tedium and sheer luck, the game mixes a lot of different codes and ciphers (from HEX, to a custom HEX like code, to end with a letters as numbers) and it ends up being very confusing. 

The time loop mechanic is a nice touch but at the end of the game it starts being tedious (take the game The Forgotten City, where there is a time loop but the game is made in such a way that you don't have to repeat unnecessary tasks each time after you finish them)

This being (angrily said), I couldn't make a equal or better game than this, I can guess the hard work designing the graphics, the sound and music, mechanics, gameplay and narrative behind this game, and it's very polished and well done (except the issues I mentioned).