As others have said Hamachi was very popular in some gaming communities. I don't know quite how it fits technologically, but a similar user experience seems to come from playit.gg[1].

[1] https://playit.gg/

My friends and I used Hamachi in the early 2000s to play StarCraft and other games over the internet without involving online services. Worked great. I’ve got a soft spot for it.