Tectoy Mega Net games
From Sega Retro
In Brazil, several Sega Mega Drive games were blessed with Tectoy Mega Net (2) support, allowing for two players to play against or with each other though the internet. With the accessory being released in 1995, worldwide support for the console and the pool from which Tectoy could import games from was starting to thin out, so in the end only five games were supported. Curiously all five games were developed by third-party companies, with no support for games made by Sega.