Been practicing trying to beat this game with no save states or rewinds on and off over the past month and finally did it, although I was still using the continue code (or cheat? I don't know what to call it, it feels too reasonable to call a "cheat"). Turns out Super Mario Bros is really fun! It's a really great entry into the NES library as a game that's simple but also genuinely challenging without ever feeling unfair, maybe with the exception of the Hammer Bro marathon at the end of 7-3. People talk about Mario controlling stiffly in this game, but I honestly don't have a problem with this game's movement and acceleration at all. In fact, I was pretty impressed by how fluid this game can feel, it encourages a flow state of running and jumping on instinct, but also rewards careful and thorough play with items to find. Don't really think it'll ever be my favorite 2D Mario, but this definitely deserves the reputation it has and there's still value in playing it today.