This is my fourth completed run through the story. I'm sure sub 40 is very doable with better routing, but especially with better execution. I am still very bad at combat in this game.

Beating this game requires defeating four elemental bosses before entering the final area.

My route here is to go fire - wind - bird - ice - electric. Bird isn't necessary to beat the game, but it does allow a few things to be skipped, and is also my best Peter for combat, so I am at least confident that it saves me time to get. Wind is definitely good to get as soon as possible, since all three of the other areas have major skips that can be performed with tornado jumps. The biggest of these skips, but also the hardest of them, is in the electric area. You'll see I struggle with that one a bit here, but it skips from the start of the area directly to the end.

Theoretically one could get wind first, but it would require manipulating some enemy AI in a way I don't know how to do, to perform a precise damage boost just high enough to reach the wind area entrance, but not so high as to hit the spikes directly above the entrance. There are a few other possibilities to get there early, but they would all require the existence of glitches that probably don't exist.

Funnily enough, I did much better on the final boss's first phase than I usually do, but much worse on Sigma Peter and the final phase than normal. Fighting Sigma Peter with Bird Peter is very easy. He has a massive hitbox to hit with your dair, and his attacks all hit in front of him, so as long as you stay inside of him you're safe. The final phase isn't that hard, but it didn't help that Bug decided to try taking on the boss himself, spawning a bunch of bombs on me.

P.S. Sorry for the super quiet audio. I was watching a movie (The Martian) while playing so I had the game muted. My review of the movie is that it was pretty good.