2XKO will have “server-based rollback netcode,” but how will this affect the game and its players?

Late last week, 2XKO’s Senior Director Tom Cannon announced something interesting on X (formerly Twitter).he announced 2XKO will have server-based rollback netcode, you can rest easy without the fear of protecting yourself from Wi-Fi warriors and their substandard connections. But this short and sweet statement begs the question: What does server-based rollback network code actually mean?

Because while rollback netcode is a known quantity in fighting games at the moment, as a technical wizardry that synchronizes game state via prediction while rolling back any miscalculations, adding servers into the mix can be a curveball for the uninitiated . What does this mean for players? Is it possible to use servers with a latency factor that doesn’t exist in peer-to-peer fighting games?

While we can’t pinpoint the exact recipe Riot Games is cooking up here, we can delve into server-based rollback netcode in a more general sense. To answer this question, I interviewed Adam “Keits” Heart. Heart is an FGC alumnus and a member of the Iron Galaxy team, having worked as a designer on Killer Instinct, Divekick, and most recently, Rumbleverse. He is also the interviewee for Infil.net’s excellent rollback article, which we recommend you read later if you want to fully understand how it works.

While Cannons and Riot Games may be working on their own server-based rollbacks, this has actually been done before. Brawlhalla – the platform fighter from Blue Mammoth Games – has been using it to great effect for years. Heart said that the same is true for Street Fighter 5, and he speculates that the same situation may be true for Street Fighter 6. While a large number of fighting games with rollback functionality use peer-to-peer (meaning a direct connection between you and your opponent), examples of this approach exist.

But, as a gamer, you might be wondering what’s the big deal? If your experience with point-to-point rollback connections is great, what’s going on here? Well, Heart lists some potential benefits of adding a server.

“My understanding of using a server with rollback capabilities is that sometimes you can’t connect to someone peer-to-peer due to a NAT setup. If you and I can’t connect, but we can connect to the server, then we can use that server as an intermediary. The only difference is that instead of going between us, my input goes to the server and then to the other player. It’s just one more jump.”

Heart continued, “Another potential benefit of servers is that if we play peer-to-peer and one of the people disconnects, there’s no way of knowing who disconnected. With servers, you’ll actually know who disconnected The plug fell off…so that provides some additional capability to deal with angry quitters and frequent disconnectors.”

But there’s one major cost, and that’s… cost. Just like the real world monetary cost. The cost of running these servers is high. Looking back at the announcement of 2XKO (then known as Project L) in 2022, Tony Cannon discussed netcode in a dedicated section. In it, he explained that network traffic will be sent between players via Riot Direct. Riot Direct, as VALORANT developers explained a while ago, is basically Riot’s own ISP. As you can imagine, this is very expensive. But Riot clearly has enough cash to do that.

While this all sounds great (especially the ability to detect and punish rage withdrawal, which has become a thorn in the side in Tekken 8), it raises a good question. If the input has to jump to the server before the player, is the added latency an issue? What about traveling across continents? According to Heart, this is where the rollback part of the equation comes into play.

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Yes, it may add a bit of latency. But if the rollback is done well, you won’t notice this. If I were playing the game at 30 milliseconds (ms) or 90 milliseconds (with rollback), I would have a hard time telling the difference, you know. To be honest, the difference between 90 and 150 is not that big (laughs).

150 MS will take you around most of the world, so yes there will be a slight increase in latency, but will you notice? No – because the whole point of rollback is that the button always pops up when you press it. We won’t delay you – if our predictions are wrong, we’ll wait for the opponent to rollback and resimulate the game to its current, accurate state when we have input from both players. If it takes 10, 20 milliseconds, that’s okay.

So, with that explanation out of the way, where do we and 2XKO go from here? Well, VALORANT’s servers seem to be performing well for reaction-focused FPS players. Assuming there are no issues there, the ball is firmly in the court of the 2XKO team to provide a rollback netcode foundation for 2v2 fighters. Hart is optimistic about their chances of hitting the ball out of the park. Plus, having Tony Cannon as a core member clearly sets the bar high, thanks to him being the creator of GGPO and Radiant Entertainment’s Rising Thunder – and playing the game online feels great.

So, with all of this in mind, it might be worth keeping an eye out for an official post or video from the 2XKO team on this topic in the coming weeks. In my opinion, the netcode is more important than the characters we will see added to the game. Netcode and online capabilities are the foundation of any good fighter, and the 2XKO team needs to make them even stronger.