Mario Kart 8 released in May of this year, after it released it only took hackers two months before they sent Luigi off the track and into space. MrBean35000vr (Bean for short) and his brother Chadderz were behind that hack (and other Mario Kart 8 hacks) and guess what? They are at it again…
This time they are set on bringing an online multiplayer mod to Wii games. That is not a typo, I do mean Wii games and not Wii U games.
It turns out that it's a bit easier to hack into the Wii than it is to hack into the Wii U, but that doesn't mean that the brothers haven't given up on the Wii U. So far they have been able to sync up data between the Wii U and Wii versions of Super Mario Bros and have only experienced longer load times and local network problems. The online gameplay itself works with "practically no latency" when on a single network, but the brothers haven't been so lucky when working across different networks. Mario Kart Wii was another game that they successfully attempted to mod.
The games with successful mod attempts released with local multiplayers, so, don't expect the mod to work on games without that feature. Once the two get the mod down to a science, they plan on open sourcing the mod.
Get a bit more info in Beans and Chadderz's YouTube video.
[Kotaku]