thanks 
glad you largely enjoyed it!
re: difficultly curve, yes, that is something i’ve struggled with in a lot of my designs so i’m really focusing on it for my next game given the lessons i learned here. i’m going to attempt a different kind of structure because i have some ideas on how to encourage people towards the content they’d like the best. i agree that it’s important to have varying difficulties instead of just a mountain with an increasingly steep slope.
for level 50, yes it’s much more open and closer to an “engineering” problem than the rest of the levels. i correctly identified it was the hardest level but i think when i made it some of my other puzzles were more open, too. as i tightened the rest of the puzzles up 50 remained as it was because i liked how complicated it was given it’s rather concise construction. but yeah, multiple testers created maps or notes to help them solve it. i think if i make puzzles like this in the future i’ll limit it to optional paths or like post-critical-path content.
one of the tricky things about designing puzzles in this game is that the base mechanics (particularly pushing teleporters) have so much complexity and nuance that it was really hard to make straightforward levels. manipulating and moving them never quite gets “simple” for the player, so there’s always this layer of teleporter tactics that sits on the player’s mental stack in addition to the core of the puzzle they’re actually trying to solve. for my next game i’m going to try to make each mechanic or element a lot more basic/fundamental so that i have finer granular control over difficulty and complexity.