Almost all of them. Back when I used to play Kingdom of Loathing (a super casual game whose main attraction is that it contains a lot of jokes), I used spreadsheets to optimize everything from which food to eat to which familiar to use when. Way back in the day, I wrote a (for me-at-the-time) math-heavy guide for the N64 Goldeneye game; I used spreadsheets for that.

I know of people who've used spreadsheets for routing speedruns of games you wouldn't think you could optimize that way (e.g. entries in the Mario Kart series).