I think lvl. 6 is bugged so I can't fully finish it, trying to contact the dev for it, but they seem to be inactive. If they see this, please add me on Steam! Or if you managed to complete the level, then please reach out as well! That being said, it took me 11h as you can see to complete 63 out of the 64 levels. I thought the game would be way shorter since most reviewers have played for way less, do NOT get fooled by their playtime. I needed a pen and paper to play it and draw the patterns I could make to unlock new levels. Sadly, the game doesn't explain things well at all. There are some drawn explanations in certain levels, but they are not good imo, I could not personally understand them. Some explanations in words would have been better!
Some useful tips: You can use the X changing line in ANY level, NOT just the ones where you acquire them. You can only hold 2 changing lines at once. You do not have to complete the levels in which you get those changing lines, simply open up an easy level, get that changing line, quit the level and you still got it. If a level is easy (for example, the first 2 levels), make sure to replay them as many times as needed to unlock every possible pattern in that level (using changing lines, of course)! Do not be like me and complete a pretty long and tedious level over and over again. I'm pretty sure every level is unlockable by completing more than one of the other 63 levels, if that makes sense.
Some of the levels are actually quite hard and you have to think quite a bit about how to solve them. Some levels are not so great because you don't even have to use certain blocks (ying yang, revert) to solve them. There is fall damage so you can't cheat your way through. The ghost mechanic is very interesting and hard to solve which is nice. The movement is quite slow and you have to be extremely patient in order to fully complete the game. The man doesn't jump too high so if you mess up your platforms you might have to restart the level. I'm not a fan of replaying the same levels in games (because of needing to unlock further levels) so there's that as well, although I do have to admit the idea of unlocking the levels based on patterns is quite interesting!
Sadly, I encountered a crash in a certain icy level, forgot exactly which number (it was the tall mountain one where you start on the left side), right when I was close to the door, it would always crash. This happened a few times until it finally worked. I have to admit I didn't pay much attention to the lessons, they were pretty interesting I have to say, although a bit weird to understand for someone who doesn't know anything about the Chinese Book of Changes which the game is based on. Overall, it's a pretty decent game which definitely taught me patience, but it can be annoyingly frustrating at times. I would give it a 7/10! Pretty addictive and fun, but it could use at least some QOL changes!
