Another case of "I don't understand the negative votes." I really enjoyed this one. It's well presented, has satisfying mechanics, and offers a good sense of progression. I did find a few minor issues, though:

-The shop is a bit awkward at first. I kept clicking the letters and nothing happened until I realized that the first two icons determine whether you're buying or upgrading, while the letters determine what you're buying or upgrading. It feels unintuitive. Considering that it takes up about a quarter of the screen, I think the layout could be organized much better.

-The game is very active and manual. The automation never really becomes strong enough to take over. It helps, but it still requires you to keep hovering over the slots, and it's much faster to play manually than to rely on the automation.

-The last upgrades are very expensive. They might make sense in the full version, since I noticed there are still locked slots (gold, emerald, etc.), but in the demo I unlocked the entire available tree, and the final silver slots and cursors feel are too expensive, I'm not grinding for that.

-There are some performance issues. When there are a lot of coins and prizes on screen, the game occasionally freezes for a few seconds before returning to normal.

-The itch.io page doesn't have a fullscreen option enabled. It's very easy to activate, there's a setting for it on the game's edit page.

Overall, despite those minor issues, I really enjoyed playing the prototype.