I really really like this! With a couple of tweaks, I could play this for a good long while. The gameplay is engaging, the presentation is clean, and the concept is smart. I have a couple of changes I think might improve it:
- I understand that the numbers scale with the number of washed plates to increase the difficulty, but I think it should happen much slower. Quick mental math is difficult for almost everyone, so using "easy" numbers will still be an engaging challenge while keeping it doable. I would probably start with just numbers 1-9, and scale very slowly (for example, introduce numbers 11-20 after 10 washed plates or something).
- The 70% washed mechanic was confusing until I got the hang of it, but it was still very hard to do strategically because the numbers were hard to calculate. The meter changing from green to blue is great, but that only happens after the player successfully hits the mark. It would be extremely helpful to explicitly tell the player where the 70% mark is ahead of time so they can aim for it. Putting a dotted line on the bar and/or actually writing it out below the wash meter would be so useful.
These nitpicky tweaks are only because I love the potential this game has. Great submission!