Grafite Sudoku - an ad-free Android sudoku with no internet permission and a built-in Academy

Hi r/SideProject, I'm a solo Android dev and this is the side project that slowly took over my last 3 months evenings. The problem I wanted to solve: every sudoku app I tried was 30% puzzle, 70% ads, pop-ups and "sign in to sync". I just wanted the puzzle. I built Grafite Sudoku mainly for myself with the following features - Free, no ads, no account. The app doesn't even request the internet permission, so nothing leaves your phone. - Classic, Diagonal (X), Jigsaw, 12×12 and City (skyscraper-style) puzzles. - An Academy that teaches real solving techniques step by step, with exercises and a final exam per mode. - A hint that tells you which technique to use and where to look, without giving away the number. - Daily challenge with streaks, Duel mode, trophies and a small gallery of illustrations to unlock. Everything is stored locally on the phone, and difficulty is about which techniques you need, not how many clues you start with. What I'd love feedback on: is the Academy something you'd actually use, or do people just want to play? Play Store: play.google.com/store/apps/details