More seriously: There have always been mobile games that have a purchase price or ask for a single payment. You could find one right now. The vast majority of popular apps have in game transactions. Game developers just want to get paid for the work they do.
At one point in-app purchases were listed clearly and prominently so they were easy to inspect (and hopefully embarrassing for nonsense like $99 wheelbarrows of smurfberries[1].) Now it seems like IAP rates are hidden below the fold, unfortunately.
[1] https://www.pipelinecomics.com/smurfberries-apple-app-store-...
So now there's an alternative way to pay. Let's be happy about that.
... actually, I just checked, and if you scroll down enough in the Games tab on your iPhone's App Store app, they seem to be running it now under "Pay Once & Play". Might be worth a look.