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Rollback netcode in Super Smash Bros. Ultimate, Dragon Ball FighterZ and Samurai Shodown being tested using emulation

Posted by Dakota 'DarkHorse' Hills • December 14, 2021 at 7:34 p.m. PST • Comments: 13

Strong rollback netcode continues to be the most important issue to many in the western fighting game community, but the titles that arguably need better online the most just don't have it.

One software engineer going by the handle of DShad, however, is currently in the early process of testing rollback netcode implementation in Super Smash Bros. Ultimate, Dragon Ball FighterZ and Samurai Shodown through the use of emulation.

This past weekend, DShad showed up with a big surprise when he posted a video of Smash Ultimate running on an early form of rollback connection between two of his systems.

The first footage looks intentionally rough, as one of the setups was connected to the internet via a mobile hotspot with zero frames of delay to cause the maximum amount of jitters — and boy does it ever jitter.

When the delay is kicked up to 2 frames though, the action appears much smoother with fewer visual rollbacks noticeable on the same connection.

This test essentially served as a proof of concept for developing system-side rollback netplay for Nintendo Switch titles.

DShad has managed to pull this off by modifying a custom version of the Switch emulator called Yuzu, and it doesn't have to be limited to just Smash either.

Theoretically, any Switch fighting game could run on this type of rollback, so DShad put this to the test by recreating the simulations on Dragon Ball FighterZ and Samurai Shodown — two fighters with the highest fan requests for rollback that have gone unanswered.

Both of the games ran much the same as Smash between the 0-frame and 2-frame experiments except that DBFZ was running at less than 60 fps, and Haohmaru starts to glitch out into the air at one point.

While this certainly looks like an exciting development for these games (and fighters in general), it's important to remember that they are running on PCs through Switch emulators.

Rollback working on Yuzu does not mean it would have the same results on an actual Switch system at all due to the nature of emulation.

According to DShad, he's managed to sync up inputs for two systems using Yuzu and make the emulator itself save and restore game states in order to predict and rollback when connected.

The rollback Yuzu mod is not close to becoming available to the general public either at this point, as the developer still needs to figure out the way to further sync up other aspects like health bars and EX meters among other potential issues that will arise.

As for if he's worried about Nintendo trying to shut down his endeavors, DShad states he isn't too stressed about it since he's modding an already existing emulator for the Switch.

Emulators themselves have been ruled as legal to own and develop in the courts. Legal issues generally arise if someone is attempting to sell emulation and of course the act of pirating individual game titles to play on them.

Similar online connection features have appeared in many other emulators in the past (including Slippi for Super Smash Bros. Melee), but it's pretty much unheard of something like this being created for console hardware that's still this recent in the Switch.

It's going to be very, very interesting to see how rollback continues to develop for Yuzu because this could prove to be game-changing for communities who have yet to receive official support for better netplay.

There just might be a handful of hoops to jump through first.

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