I have only just unlocked the green ball, but ideas I would have so far would be to have the play area central and a little larger. Also further possible upgrades for a game of pachinko would be % chance increase that pegs send balls left or right. An upgrade to this could be that the bottom row of pegs launch balls to the left or right rather than just nudge them.
I am guessing that it would be nice to be able to turn off the auto on the lower level balls once the higher level balls are going quickly. With hindsight, this is unnecessary, both because there is no collision between balls and because the basic ball is the most profitable until WAY into the late game.
While it is nice that the balls don't actually touch each other, allowing for many balls to occupy such a small space, it does make one problem apparent. I have a green ball stuck on a peg. With no contact between balls, I am guessing that this peg will remain here for ever. So either the pegs need to be truly round or there needs to be a nudge button like on a pinball table, to free any stuck balls.
Actually, maybe only one peg has this issue as all the other pegs seem to work properly. It is the second row from the bottom, the peg above the right hand x2 slot. I wonder if something was overlooked in the design of this particular peg.
Its relatively easy to max out the first ball so you have 200 $1 balls being produced every second. The green and yellow balls take forever to catch up, assuming they can also go down to 0.05s. But as you have an idle game planned based on this, there will be other aspects to focus on.
The yellow bar seems to hit 100% a little past the visible part, like full is actually only 95% full.
After leaving the game running for a while, it seems that many of the pegs have a ball stuck on them, though it is hard to tell as there is a constant flow of balls.
And even with 9 green balls every 0.88s, white is still more profitable.