As much as I love touching hardware and registers, I have enjoyed using Butano, the asset-abstraction framework for GBA, for the last 2 years. I want other people to enjoy it too
I am halfway through my 6-part series on building a puzzle game with it. I choose Klotski (sliding rectangular block puzzle), which has its pros/cons
Pros:
Simple mechanics
1 entity type
Simple rectangle collision
Cons:
All the characters are straight