Nintendo Switch Online has been hacked within hours of its release, and players have already figured out how to play their own ROMs as well as the 20 NES games that come with the service. The process through which they’re doing so is reportedly easy enough that most fans will be able to replicate it, if given instructions.

The first video of a player launching a game that is not included in the official offerings was released last night. You can watch it below.

You can watch another short clip of an uploaded ROM being launched below.

ok so

this is incredibly basic but it shows that fully custom games ARE possible!

hakchi for NES Nintendo Switch Online when?#NintendoSwitch #NintendoSwitchOnline #NES pic.twitter.com/OBYn3dLOtV — kapu | the Gay. (@KapuccinoHeck) September 19, 2018

It turns out that the emulation used for these NES games seems like a direct port of the software used in the NES Classic Edition, which makes it very easy manipulate. The NES and SNES Classic Edition have been opened to allow the addition of new games for some time now, and doing so is a simple process at this point, even for laypeople, using a program called hakchi. Doing so fixes one of the system’s most annoying issues, in fact.

good lord #NintendoSwitchOnline's NES games are plain .nes files

GUI appears to be entirely LUA much like the S/NES Classic so people are gonna be able to go to town on this



The "database" file that contains a listing of all valid games is plaintext,- pic.twitter.com/bO8M4B7U5e — kapu | the Gay. (@KapuccinoHeck) September 19, 2018

So how easy is it to add your own ROMS to Nintendo Switch Online? We asked kapu, who wrote the tweets above, and who spoke with @OatmealDome and @Master_F0x when answering our questions.

“For someone without prior experience in running Switch mods, getting all of it set up at first is a bit of a process, but nothing too hard with proper instructions,” he told Polygon. “After an initial setup it’s insanely easy to swap out ROMs and add entirely new ones.”

He thinks that the ease in which players can add their own mods is just a side-effect of Nintendo making it easy to add new games in general.

“I have serious doubts that it points to any vulnerabilities, I’d say it’s just a side-effect of making it easy on them to add more games as they officially release more, thus making it easy for modders as well,” he explained.

It feels pretty much like an afterthought. The most work that went into it was likely the UI. There aren't any fancy patches for individual games or anything, the online multiplayer aspect uses the exact same networking code as any other Switch game, such as Splatoon 2 or MK8D. — kapu | the Gay. (@KapuccinoHeck) September 19, 2018

The big question is whether Nintendo can, or will, ban consoles for uploading their own apps onto their Switches.

“From what I’ve been told, there’s a fair amount of telemetry and checking on the app for a valid setup, but ultimately I’m unsure,” kapu said. “Nintendo is very unpredictable when it comes to these things so for now I would heavily advise against anyone else doing it.”

To keep things simple, maybe don’t mess with this if you don’t already know how it was done. What’s important is that it’s possible, and it’s very unlikely efforts to hack Nintendo Switch Online will stop here.