You go down, down, left, left, up, up. The squares making up the shape of the 'u' are the same as the shape of the rooms you trace, if that makes sense. Start at the first stone tablet pointing down, go left at the big one, then up through the lava rooms.
Ooh, that could work! I may have made the game a bit too esoteric ;>.> If you want to get through the crystals, take a look at the room with the roman numerals and the inverted cross. I intended you to need walljump for it, but I think there's a way you can do it without as well.
Edit: For the double jump puzzle, you can also follows the arrows on the stones. There are some in the lava rooms that are melted (in an attempt to obscure which way the arrows pointed), but the implementation is subtle... It's hard to judge what's obvious or not when you're the one building the game.
The room with the plant NPC, that has a big column through the center. The one above the starting room. I also had the series of transitions wrong in my hint doc, so double check that. I had one extra down and right, I believe.
I also think I'm gonna just... include the dev map in the solution doc XD
Edit: Dev Map added!!! For you visual learners out there. Plus it's cool to share some of the stuff that went into making the game :3