The rulebooks are the worst part of the hobby. Some are beyond awful. One Deck Dungeon took me several attempts and a few google searches to figure out.
Another bad one was the travel version of Azul, which assumes you have already played the full size version.
I also watched a few videos to understand one deck dungeon, but it wasn't until I bought the mobile game that I really felt like I knew what was intended.
Another bad one was the travel version of Azul, which assumes you have already played the full size version.