Congratulations! Simple ideas are often the best and a small scope is exactly the right thing to aim for in a 20 second game. I like the subtlety of the Visually, this is looking very good. The colour scheme is well chosen and the simple shapes are very effective. Music and SFX are working nicely.
If you are looking for ways to make improvements I don't immediately see many. You could add extra juice and maybe emphasise the relationship between broken parts and improved odds with some kind of visual connection (e.g. when the fan stops spinning, you have an attention grabbing throbbing animation around the fan *and* the changing odds display.
You could definitely consider developing this into a larger and longer (but still simple) game outside of the jam.