Nice little world you got going. Came here after realizing there were more games before the Chronicles arc was first released. I can't wait to spend all weekend trying to catch up. :P
I noticed that it seems like both modes have about the same difficulty, making the game replayable between them, though some puzzles specifically have varying difficulties base on the mode. The blocks not being marked in Classic Mode makes it a bit more of a mystery as to the flow of the Unpuzzle, while the Fast Mode forces a certain flow that may be harder to solve than an open-ended Unpuzzle.
Not gonna lie. I thought this was a pretty easy game, until the 3D kicked off, then while it was still not too difficult, it added an excellent depth to the game.
Um, the cave by a traveling merchant, which you enter by going down into a tree, is it purposely a dead end? Not to mention, moving the rock glitched me into being trapped there... I mean really, what the hell!
 "Medieval Cop - The Princess and The Grump"){kind=icon}
 "UnpuzzleX"){kind=icon}
 "Unpuzzle 2"){kind=icon}
 "Elements"){kind=icon}
 "klocki"){kind=icon}
 "Coloruid 2"){kind=icon}
 "Cube Escape: Theatre"){kind=icon}
 "Cube Escape: Birthday"){kind=icon}
 "Cube Escape: The Lake"){kind=icon}
 "Orbular"){kind=icon}
 "The Last Door - Chapter 2: Memories"){kind=icon}
 "Disaster Will Strike 2"){kind=icon}
 "You Find Yourself In A Room"){kind=icon}
 "Legend of Pandora"){kind=icon}
 "Submachine 8: the Plan"){kind=icon}
 "Submachine 7: the Core"){kind=icon}
 "Reactance 2"){kind=icon}
 "The Space Game: Missions"){kind=icon}