Don't be fooled by this game's price and appearance, the standard store page description, or the easy puzzles presented in the trailer and screenshots. This is a very difficult Sokoban game--too much so for me. I would normally not write a negative review of a puzzle game for that reason, but it seems appropriate here.
At first, it was refreshing to see that the developer didn't take the typical puzzle game route of making half the game so easy as to feel like a series of tutorial levels. The difficulty ramped up quickly even in the single-digit levels, so it seemed like I had a lot of clever puzzles ahead of me. But even by just the middle levels, it became obvious that the puzzle difficulty advanced mostly by becoming more tedious and space-restrictive: the 72 levels never get bigger than around 8x8 (most are smaller), but they do add more and more blocks to be moved.
Levels sometimes felt like they were generated by computer to be difficult in the worst way, i.e. by requiring too much planning and foresight, too much time, and too much precise fiddling with individual blocks for the average person. (This feeling of computer generation was strengthened by the occasional appearance of a block with no available move or only one possible move with no impact on the rest of the level, which is pointless.) Accordingly, they felt like a chore to complete and rarely gave me the satisfaction of an "Aha!" moment. I confess that, in the absence of a walkthrough past the first 11 levels, I had to resort to a Sokoban solver from time to time so that I could unlock more of the game. After seeing some of the solutions, I had to laugh because I probably would have never been able to achieve them on my own.
At the same time, the difficulty was somewhat inconsistent. On more than one occasion, I struggled with one level, then breezed through the next few. This usually happened when a level with many blocks was followed by levels with fewer, i.e. when a tedious level was followed by shorter levels that had to be more clever because of their simplicity.
There are also problems beyond the difficulty.
Annoyingly, levels are locked until the player completes the preceding ones. If the player gets stuck on one, he cannot play the rest of that area. Since the game has no story, has no leaderboards, and introduces no new mechanics, there is no good reason for this restriction. Furthermore, due to the difficulty of the game, most players will never see some of the levels. Many may only complete about half of the game.
Although there is an undo button, there is no option to save the current state of a level. Since some of them require a lot of time and planning, players will lose a great deal of progress if they choose to quit or if their session is interrupted.
Finally, despite the different themes (sand, stone, etc.), there are no differences among them besides the backgrounds. A purely aesthetic change would have felt more complete if the blocks themselves, both movable and immovable, were themed. For example, the grass world could have featured trees as immovable blocks. Non-aesthetic changes could have involved changing level sizes or layouts. For example, a forest theme could have featured a large number of single unmovable blocks (trees) that the player must work around while desert levels could be more wide open.
At only $1, I can't expect much in the last regard, but I don't think that unlocking all levels and adding the ability to save would have involved much more development time.
In any case, my chief problem with the game is its difficulty. At the time of this writing, the current area completion rates (~1-2% before a guide was posted), reviews (including positive ones), and discussions show that players who can complete these levels are few in number or have not yet discovered the game. However, if moving 10 blocks around one space at a time within a 5x5 area to try to find the 250+ move solution sounds like your idea of a challenge, then this is the game for you. I'll just stick with the SOK series.
