I really love the artstyle and the graphics! The music is really catchy and good! The sound effects of hitting your balls against the employees was a little grating though after the third wave lol
Unfortunately the theme criteria wasn't fulfilled very well in my opinion (very creative though, still) because the only spinning element here would've been the one-armed bandits and none of them actually do spin (or move at all for that matter).
It could become a pretty cool full-fledged game (and maybe better fit the theme even) if the one-armed bandit was a roulette-table instead and you'd give that some interaction possibly with the ball you throw. I could imagine when you hit the roulette table, it spins the ball on that table and you can throw one ball (upgradeable) to knock the roulette table ball away from wherever it would've landed to give it kind of a second wind.