I slayed the beast!
There's certainly a sense of progression, during my first few runs, I couldn't get past the skeletor spam period, after that my first reaction to the onis' damage output was "Are you kidding me", with the final boss getting me to admit defeat in my hearts of hearts the first time I saw its HP. But the learning curve works very well, I got farther with each try, slowly learning how I should balance my deck (though I'm not really experienced with deckbuilding games, so I dunno how people with more experience in the genre would fare). I had fun, it got very hype at the end when you just play 20 cards a turn. Thank you for finally letting me experience that feeling of being a pro Yugioh player.