I actually managed to get all the runes in a playthrough. One of the sublevels near the end was definitely the most difficult. Crisp Lad calls it the flappy bird level lol. There is actually a way to have more fine control in midair, and I found it in that level actually. If you're pressing w while doing a or d, you travel less horizontally than if you're not pressing it. I really think that's the only way I was able to beat that particular level. You get a lot more fine control if you're pressing it, and a lot more distance if you're not, further jumps and all. It kinda felt like a hidden mechanic to movement like you can get in Rainworld when I discovered it, but it wasn't something we planned.
Ohhh, I love this. In our first Steam game we've actually discovered a "broken" jump if you press buttons in a particular order. But we decided to keep it and let players discover it.
Again I'm not saying it's a bad thing, just saying how I felt while playing, haha 😀 I think I just wasn't in a challenge mood