This itch.io feature is pretty great!
Having played a lot of the ICB arcade machine, one difference I noticed right away with the physics is that you fall in holes much more easily in TumbleSeed.
It looks like TS checks if the center of the seed is over a hole, and if so you fall in. This means you could fall in a hole that is smaller than the seed itself, or more relevantly a gap between the bar and the edge of a hole smaller than the seed. You also roll into holes you would roll in front of in ICB.
To be more like the physics of the ICB machine checking a point straight down from the center, maybe 1/3 or 1/4 of the radius from the edge, and a point 1/3 or 1/4 the radius above the top of the seed when rolling along a bottom edge of a hole. And the top and bottom points on the seed for the top edge of a hole. Then if either of those 2 situations is true fall in.
Not sure if that would mess up game balance or not having not gotten too far yet. But just thought I would mention it.
Love the game so far!