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.
