Thanks for the game!
It was very enjoyable to play! I was expecting some bugs that would break the mechanic and I wouldn't be able to complte the puzzle, but have encountered none. Considering how many different mechanics you have in the game, and how well difficulty curve is executed, this is quite an achievement in my eyes! I also liked how unexpectedly logical some of the puzzles were (pushing the block through the gate was my faworite).
With that said, while the last two-three puzzle pieces felt exceptionally tight, the beginning of the game was somewhat sluggish. This is mostly because puzzles rarely forced me to think about the position of my older/younger self strategically, so several times after significantly forward with younger self, I was forced to re-track same distance by the older self when younger self reached the impasse. This, combined with big distances and slow movement made some of the puzzles at the beginning somewhat tedious.
There were also two moments that I consider as bugs: 1. in the long stretch of plantable tiles section there was a moment when I was unable to get down the wall by the wine, since only 'plant seed' option appeared when I approached the wine; 2. from the wall in the last section (behind the dragon and block-unlocked gates) I was able to see my reflection in the riwer, but no interaction were availiable. That looked strange and almost convinced me for a moment that I've encountered a game breaking bug.
I sometimes found myself having trouble understanding 'when' exactly am I now. I would be cool to have two different times more visually distinct from each other, for example, have other color for grass and trees in the future.
Overall, the biggest downfall for me was lack of a meaningfull ending. I've collected all the crystals, and nothing happened... I tried to blink myself out of existence by rapidly switching selves several times in a row, but failed at it.