Maxwell's puzzling demon

Best designed puzzle game ever. There is so much creativity in the puzzle mechanics. There is so much content, There is no other game which will make your brain melt so intensely. I cannot imagine anything coming close to this. If you think you are good at puzzle games, play this and reconsider. Be prepared to put some hours into it, you will need them. It's just peak game design. Nothing to add.

Arguably the best puzzle game design ever. Other puzzle games usually introduce a new mechanic every few levels to keep things fresh. In Maxwell's Puzzling Demon, there's the base mechanic of hot and cold, and during the game only 2~3 other gameplay elements are introduced. Yet there are hundreds of levels in this game, because literally all the mechanics, even the ones you don't realize are mechanics, have interesting interactions that are squeezed to their maximum potential. Another point is that the level design is really, really solid. The levels also get really, really difficult, but the game has an interesting hint system for the main levels, where you get to solve a simplified version of each level. If you're up to the task of bashing your head against some really tricky sokoban'ing, then look no further.

Don't be fooled by the simple graphics. This is one of the cleverest and best block pushers ever made. Straightforward mechanics unfold into shockingly sophisticated systems, and the puzzle design is consistently excellent. Deserves to be mentioned alongside Bean and Nothingness.