Hey,

I built Flappy Bird in Google Sheets w/o using App Script. It's entirely built using cell formulas, conditional formatting, and an unpatched server side validation. (I learnt of it's existence here: https://docs.google.com/spreadsheets/d/1KAauJp9MiblyAInIbgS2...)

I decided to build this after coming across https://eieio.games/blog/realtime-google-sheet/, though I think in some ways mine's a lil more advanced.