Thank you for suggesting the Hold function, I was able to have a lot of fun with that! It certainly makes it feel more like a traditional Tetris game. I did come to realize that with the 1 turn combo forgiveness, it made the game perhaps excessively easy after a while, but it was very nice to get my bearings and make progress with it. I was able to actually turn my focus to trying to get 5x3 cakes and such!
When I don't use the hold cheat, now, I'm able to clear the Marathon: Normal practice consistently but the best I've done on Marathon: Hard is 120 lines. It feels like I must be missing something fundamental because I'm barely making any incremental improvements at all after many attempts on it.
If I could get some early insight that would be put in the downstacking tutorial, I'd really appreciate it...