Great game and you lied in level 6
Haha, yeah, a lot the puzzle I knew could be done with only 2 Demons, but I didn't know there would be so many. For most of them, I decided I preferred to leave lost of stones and all 3 demons so people can solve them how they want.
By "only one gem on call Surgat", do you mean "one yellow gem only, and it's on Surgat" or something else?
Those are the levels I dindn't manage to do with only 2 demons:
10, 12, 13, 17, 23
And of those I think 10, 17 and 23 are impossible to be done with only 2 demons (for 12 and 13 I won't make any affirmation but they most likely aren't solvable with 2 demons too).
If you want I have screenshot of each level I solved using only 2 demons to prove my claims.
I fully believe you because I've beaten all of them you said you did. 23 can actually be done if you just loop a single pattern, 13 and 17 I haven't even found a "2 Path Clear" (you use one Aratron stone to activate the other two, it's technically 2 demon but also not?) for those two, like NuSan has 10 and 12.
I uploaded a video of all my 2 demon setups if you're interested in seeing what I did, but I'd love to see your own screenshots too. You could've found fewer stone/fewer step setups. Hit me up on Discord or smth so it's easier if you wanna! (@holoknight)