I have already passed all the levels but there are so many hidden achievement that i don't know how to trigger

I tried solving Chapter 15, level 19, but it's impossible to get the ghost cube to walk 5 squares downwards to the exit, because the original square on the left cannot walk 5 squares upwards, only 4, before reaching the cube change switch. I looked at the YouTube walkthrough for this level, and it's of a previous version of the level with no sand squares. Translating a conversation in the comments of that video, I see the video creator solved the level in a simpler, unexpected way (walking to the exit di...

I see there's no guide available. A quick Google search didn't show one either. I'm halfway through Chapter 4 and it's massively slow going. I think I'm spending 20-30 minutes per level. I see others have gotten through much farther. Am I the only one finding this game difficult? The achievement percentages seem to indicate a decent number of people made it all the way through. This seems like the kind of game a lot more people would have played. Wouldn't someone have made a walkthrough?...

I have no idea anymore

It's the last achievement I don't have and I tried a lot to find it but without success.