Proposed To: AAA Gaming Companies (i.e. Capcom and Nintendo)

Purpose

            This is a report detailing the advantages of implementing roll-back net code into online fighting games.

Summary

            In fighting games, it is important to know exactly when your opponent is doing something and what it is they are trying to do. Most of this is figured out with starting frames, the first few frames in a sprites animation which gives players a hint on how to combat the move. When its clear what it is your opponent is trying to do, it would be easy to combat it. However, playing these fighting games online is frustrating because of the severe lag that is brought through network issues. Most games use delay-based net code to solve these network issues, and I am proposing that we start to switch over to roll back net code for the reason of it being more reliable and for the fact that it can bring in more customers to play the game online.

Introduction

            Net code is a term that most people that are apart of the gaming and game development community use to describe the way two computers talk to each other. Many online games have unstable network communication due to the distance that each player is from each other. However, fighting games that are played online have it much worse as the connection solely depends on two people, rather than a whole team, causing the game to lag.

            Most of the fighting game industry tries to combat the lag when two computers communicate with each other with delayed based net code. To combat lag in game, making sure every frame is shown, delayed based net code will delay the users’ inputs. Meaning, when one person hits a button, both players must wait for both computers to get the signal of what button was just pressed. This is known as input lag, and, if anything, makes things worse. Input lag is not something that comes purposely with delayed based net code, it is solely because of the unrealistic expectations delayed based net code has for it work. When a game uses delayed based net code for their online games, it is with the assumption that both players are geographically close to each other and using some sort of ethernet cable connection. It is because of these strict assumptions that causes the game to start lagging. Additionally, according to Polygon, this heavy lag changes the way the game is played and how players win. “Players may also find their inputs lost in the transmission somewhere, often compromising the outcome of the match. Winning may not come down to who has the best strategy of execution, but rather who was able to adapt to the shifting, uncertain nature of the net code more efficiently.” (Cabera, David. Polygon 2020)

            Roll back net code, in short, is a smart AI that acts as a spectator during an online game. If two players are in the middle of a fight and there is a scenario where it is taking a long time for the input commands to reach one another’s computers, roll back net code will start to run a simulation of the ongoing game. Basically, when a lag spike occurs while waiting for the inputs to reach the computers, roll back net code takes control and starts to predict what it is that each player was about to do based on their previous inputs. For example, if a player was walking forward before and a lag spike started to occur, roll back net code will see the pattern of the player and will continue to move the player forward. This act of predicting makes sure the game never stutters or lags as the game no longer waits for the computers to receive the inputs.

            However, AI is not completely perfect, so roll back net code does have its chances of messing up. Its prediction of what the player was going to do can be wrong, and in that case then what? If the AI were to get the prediction wrong, what it will do is “roll back” the player to the input that they actually pressed. This is done by quickly changing which frame the player will do a move. For example, if a player was going to hit a jump input, but roll back net code predicted that they were going to continue to walk forward, roll back net code will quickly revert the player a couple frames back. After this, they will take the starting jump frames, and cancel jumping on frame 1, and instead start the jump on the 2^nd or 3^rd frame. This quick correction is nearly impossible to notice, and when it is, then that is just a small price to pay to have much better online. With much better, and playable, online, all the downside that I stated previously with delayed based net code are fixed.

Proposed Tasks

            With roll back net code implemented into the online of fighting video games, the following task’s will be able to be performed.

Task 1: Giving the video game a better network/online

Delayed based net code automatically assumes that both players are geographically close to each other and using ethernet cable connection. With these conditions, online should run smoothly, however it is foolish to assume that this perfect scenario is always met. So, when these unrealistic conditions are not met, the game would delay the users’ inputs, making everything stutter and choppy. This is because when you hit a button, both, your computer and your opponent’s computer wait to get the signal. This causes all sorts of lag, most notably input lag.

With roll back net code implemented into the online of these fighting games, any type of lag, such as input lag, will be eliminated. Roll back net code simulates the game during these lag spikes, basically taking control of everything, moving the players itself through its own predictions. These predictions are based on the players inputs, and if roll back net code were to get its prediction wrong, it quickly corrects itself when the inputs are received. This basically holds the hand of the network, so whenever it lags, the players will not even notice it because of how fast roll back net code is to simulate the game.

 Task 2: Increase of player/copies sold of the game

             Delayed based net code caused bad lag, which hurts the player and the sales of the game. According to a research study named “On the Battle Between Lag and Online Games”, the effects that lag has on the perception of the game is strong. In this research study, a wide variety of participants were asked multiple questions regarding lag in online games. “If players are asked about the connection between lag and a game they decided to quit, roughly 57.6% of players say there is a moderate or strong connection…”(Kuan ta-Chen et al, 5) A majority of people claim that if they are to experience lag in an online game, they are most likely not to pick up that game again. This hurts the sales of a game as most online games are sold by word of mouth. Friends tell friends to get the game so that they can all play with each other, however when the players do not want to pick up the game for the reason of the online, not much new people will be attracted to it. However, with roll back net code, and ultimately a better lag-less online experience, more players will be engaged in the game as they can play it without frustration. This will build a stronger fanbase for the game and, as the results of the experiment can be flipped the other way, players will tend to pick up the game again more and more.

Conclusion:

          It gives me hope to see how some video game companies are starting to switch there net code to roll back net code. In June of 2021, the video game company Arc System Works (ARC.) will be releasing one of the most anticipated fighting games of 2021, Guilty Gear Strive. One of the most exiting pieces of information about the game was the fact that it would be implemented roll back net code. After the second online beta test for Guilty Gear Strive testing out the roll back net code in the game, Arc had gotten a lot of praise for their decision of switching from delayed based net code to roll back net code. “Players in the Guilty Gear Strive Beta have been praising the rollback net code. The beta had its share of problems, but when the servers were up the game was incredibly lag free. Personally speaking, I’m particularly happy for those who usually can’t play with anyone else but other players in their regions. I’ve most notably heard of South African players happy they can finally join the worldwide scene on GG Strive. The game’s net code is definitely a huge asset. Especially during a pandemic. Hopefully more developers will learn from it.”(Agossah, Iyane. DualSHOCKERS. 2021.)

            It may seem weird for people to rejoice more about the games net code rather than the content of the game, but that is just how much good online matters to people in the fighting game community. Getting rid of lag makes these games playable online, allowing more people to enjoy and get better at the game. With roll back net code solving most of the problems with online game communication, and due to the fact that most consoles (Playstation, Xbox, Nintendo) require to buy a subscription for online, it is not right to give the consumer bad online.

Resources

1. P. Tseng, N. Wang, R. Lin and K. Chen, “On the battle between lag and online gamers,” 2011 IEEE International Workshop Technical Committee on Communications Quality and Reliability (CQR), 2011, pp. 1-6, doi: 10.1109/CQR.2011.5996093.
2. Cabrera, David. “Bad Netcode Is Killing Many of Your Favorite Fighting Games.” Polygon, Polygon, 25 Mar. 2020, www.polygon.com/2020/3/25/21192522/netcode-samurai-showdown-fighting-games-rollback-delay.
3. Pusch, Ricky. “Explaining How Fighting Games Use Delay-Based and Rollback Netcode.” Ars Technica, Ars Technica, 18 Oct. 2019, arstechnica.com/gaming/2019/10/explaining-how-fighting-games-use-delay-based-and-rollback-netcode.
4. Agossah, Iyane. “Arc System Works Comments On Rollback Netcode In Guilty Gear Strive.” DualShockers Inc, 21 Feb. 2021, www.dualshockers.com/arc-system-works-comments-rollback-netcode-guilty-gear-strive.