https://arstechnica.com/gaming/2023/04/wi-fi-in-an-nes-cartridge-super-tilt-bro-takes-the-1985-console-online/

In the heyday of the NES, if you didn't have a human nearby to play games with, you were out of luck for multiplayer gaming. But thanks to a new NES cartridge inspired by Super Smash Bros. for Nintendo's 8-bit console, you'll be able to play a new homebrew game with anyone on the Internet.