One of those rich people looks VERY familiar, lol.
That aside, it's a well made game. I like that the visuals are very approachable since it's meant to be cathartic. The music fits well.
I do think there may be a glitch. I hammered several wealthy people and when I hit one of the normal folks by mistake the game over screen stated that I hit 0 billionaires or something to that effect. But I know I had to have hit at least a dozen or more. If it is supposed to say 0 you may want a stronger indication that the A.I. that replaced you erased your progress or something to that effect. Then again that may be the product of reach double digits and the number in front of the zero just wasn't visible. I played it twice to test it and the second time I hit a normal person on purpose and the number did change.
I think as a short game is works well, but I think you missed an opportunity to use those windows. Having someone where green was a really smart idea to trip up the player but if you revisit this game or expand - make use of the windows as a way to distract and break up the monotony a little bit. Have a plane fly by or have a
little guy appear to wash the windows. Those could be fun.
Lastly, I did love the gasp everyone utters when you hit a normal person by mistake. It REALLY magnified the consequence and that was great touch!