Wow, just- WOW!
I was a bit sceptical at first as the artstyle didn't really hit me. But that doesn't matter too much as the game itself is really REALLY good! Puzzles like these tend to be somewhat annoying in other games, being a bit "in the way" of storytelling and not well refined. This though was really fun, Puzzles have great mechanics that are introduced in a reasonable way. On top of that, they just make sense, both story-wise and thematically.
Playing on hard really made the time limit a potent enemy here and there, whereas in other instances the focus was more on just understanding a complicated problem. I like how both come together in the end. Only thing i really struggled with was the lava-run, but that was mostly about me being a bit clumsy.
Over all this is one of the best rpg-maker games I've played, and I can't wait for future updates! I can see though how coming up with new and interesting puzzles is hard and takes lots of effort. So don't feel pushed, just lots of motivated ;)