Beautiful art. Difficult economy*.
Right off the bat, the art style is fantastic. Color palette, hue, brightness, and style all fit together harmoniously. I loved the attention to detail like the little motes of dust floating around. Gave a distinct moldy gambling dungeon vibe. Based off some of the items, I suspect there may be a Binding of Isaac player or two among the group. :)
I struggled for a bit figuring out what exactly to do. I think what confused me was the displayed probabilities above the machine. I thought these might be the natural odds of each symbol showing up before any other auto-win percentages applies. I spun quite a few times before convincing myself that you must need to actually spend some items in order to win. I had also managed to get into a state where I had no items but I was still allowed to spin, where it seems that I should have just lost at that point.
After arriving at the correct understanding of the mechanics, everything made a lot more sense. I still wasn't really able to pop off with my items for very long, though that might just boil down to a skill issue* in learning what works and what doesn't. I would probably need a "baby's first gambling apparatus" mode to go easy on me while I learn the ropes.
Overall, though, the gameplay loop and systems seem very solid! I thought the mechanics were quite apt for the theme. I definitely felt the pressure to throw an apple or two on top of my good items in order to boost the odds of a win. The times that you lose out to the 1 in 5 explosion really keeps up the suspense.
Awesome job!
*edit: I came back to this later and it was definitely a skill issue. The failure in my strategy was over-committing bets and neglecting the upside of breaking the machine. You get a replacement item for winning, but also some item from the machine when it blows up. If you split up your items when there is no apparent synergy, you have more chances to earn a combo item from the machine one way or the other. So before (bad): bet 5 apples => guarantee one win and one explosion item. After (good): Bet one apple at a time 5 times => there is a tiny chance you don't win or break the machine on any of the spins, but more likely is that you win some item from the machine in the middle of those 5 bets. You now have more options for any of the remaining 5 apples you didn't use to make the next spins even better. After cleaning up my game, I was indeed able to pop off a few times. It became a lot more enjoyable after that.