Patrick's Parabox is a puzzle game about boxes within boxes, it's an absolute gem and I've had a fantastic time playing through this one. Note: key provided by the developer.
The reception to it seems to be great too, with a Very Positive user rating on Steam. It has less than 500 reviews right now though, which means plenty of people don't yet know about it. A shame, as puzzle game fans absolutely need to pick up and play this one and I truly mean that.
You've played Sokoban block-pushing puzzle games before I'm sure but nothing like this. It will at times melt down your brain and stuff it into a box. The idea is that you push boxes inside other boxes, that all need moving around into the correct positions. It constantly mixes it up and throws in little new mechanics and it's pure joy to play through.
When you eventually get to levels of boxes within boxes within boxes of recursion, it can get challenging. However, Patrick's Parabox is careful not to truly overwhelm you. It's graceful on how it handles the difficulty that never feels ridiculous and I love it.
Could easily be the Puzzle Game of the Year.