I've been reading "Level Design: Concept, Theory, & Practice" by Kremers. It's a dead-tree book, and more of a theoretical treatise on all kinds of level design concepts, tropes and patterns rather than a hands-on guide, but might still be of interest to you.

Same. Anyone know of a similar book for 2D level design?

Some random search results:

- https://www.tadeasjun.com/blog/2d-level-design/ mostly talks about Celeste

- GDC talk from Maddy Thorson linked from that post: https://www.youtube.com/watch?v=4RlpMhBKNr0

- previous HN post (original link seems to be dead) with links to other talks: https://news.ycombinator.com/item?id=20177157

Not a book, but Cave Story is interesting because the first areas in the game are too large and shapeless, but later areas are very well defined. I feel like the author went through some sort of level design progression while making the game.

Found this paperwork on a framework for platformer level design: https://eis.ucsc.edu/papers/smith-sandbox-08.pdf

Seems a lot of it applies to 2D levels too, I did some quick skimming and didn't see anything that jumps out as not being applicable for 2D levels. Anything in particular that seems very 3D focused? I know the images happen to be 3D, but most of it is basically the same for 2D.