Leaflet is fantastic. One of the more interesting use cases I've seen for it is the Guild Wars 2 wiki. They use it heavily to display the game map for regions, areas of interests etc. It's quite impressive, and very useful as a player!
It's not even just video games! Leaflet's great for real-world non-video games maps of the whole world. It's by far the easiest system to make any random old image zoomable and pinchable.
My brother and I created a map of our local Costco in Figma and just put it up at https://costcomap.com/
This got me wondering if my favorite game as a kid, RuneScape, also uses Leaflet on their world map for Old School RuneScape (the version I am more familiar with). It turns out they do. Cool!
Right, leaflet can be used also outside the map context. We used it to reimplement a "Pick Your Own Seat" component (originally implemented in flash), where the user picks its own seats while buying tickets!
I'm a freelance web developer for https://gamerguides.com/ which also uses Leaflet for video game maps. It's a little weird to get working with at first but it turns out it's well suited for that sort of use case. I love it.
https://wiki.guildwars2.com/wiki/Kryta#Interactive_Map