I like this game, I think it has some difference with the ball&peg games I've played, and the upgrade description is quite clear.
some suggestions I have while playing:
1. it would nice to give player more hint the order of ball dropped, at first I thought the top ball goes first.
2. it would nice to check the upgrade on the peg/ball/bucket by clicking them.
3. it would nice to popup a confirm dialogue when player try to upgrade and replace a item with existed upgrades.
I personally feel the board is too large so it might take looong time to fill everything lol. But that might be intended? Maybe it's better to start with smaller game zone and increasing it?
other than that, very interesting and addictive game!

Thanks for the kind words, glad you enjoyed it!

Each one of your suggestions was already on my to-do list actually! 

I plan on finishing up the Upgrade Info Popup today, I'm going to add a down arrow to the ball on the the bottom of the list so that's a little more clear and I agree on needing to improve the UX for over-writing an upgrade. 

These changes should all be in today or tomorrow and you'll be notified when they are.

As far as the board orientation, I do have plans to add additional board layouts in the future as part of a larger update to increase the replayability even more, and a smaller "intro" board would be a part of that.

Thanks again for the thoughts and feedback!

Added the Upgrade Info Popups, wasn't as bad as I thought and you're 100% correct, they are very helpful. Thanks again!