EventSheet
Looking back, I definitely should have started moving off of spreadsheets at this point, but it's really easy to stick with what you know. I've since learned to push past that. Anyway, I used to play Hypixel Skyblock a lot and was interested in becoming very rich in it. The best methods were all about trading, so I made a spreadsheet for it. The first versions were usable but very hard-coded.
I used them, made lots of money, and actually sold some versions. Then people said, "Hey, you should redo this but better, and I would pay real money for it." See, I was just selling it for in-game coins. So I did. Versions 1.1, 1.2, 1.3, 1.4, and finally 1.5, the magnum opus. It had almost all the well-known money-making methods, plus some obscure ones I'd discovered myself. Lots of in-game coins were made, and on version 1.5, some real money too. But it's a spreadsheet. You're not making thousands. It was just a couple hundred.
It's really hard to make a spreadsheet into a webapp. The user needs to input data, and there's no easy way to do that without giving them access to ruin the whole thing. My workaround was to have two linked spreadsheets that share data. One of them imports data from another where the user has edit access, and the other one (which the user looks at for information) they only have view access. You could easily swap out the input sheet, and the data sheet stays safe.
Also, you may be wondering how you're getting live data from this game using a spreadsheet? Well, let me tell you, this spreadsheet had a backend. Yep, that's right. I had a Python script running on my computer 24/7, updating a master sheet. It would write to the cells, and all spreadsheets of this project would import data from that other master spreadsheet and filter and do whatever with it based on the user's inputs. What a time.
