Rocket League on Unreal Engine 5: Expert explains what it could mean

On Friday, Psyonix accidentally revealed in a job posting that Rocket League is being transitioned to Unreal Engine 5. The news was first reported by YouTuber and Twitch streamer Goldfish. Psyonix later altered the posting to remove the Unreal Engine 5 bit, but did later confirm on Reddit that it is actively being worked on as “a long-term project.”

With many fans confused on what the changes could mean for Rocket League, a game that still runs on Unreal Engine 3, “Rocket Science” YouTuber HalfwayDead set out to explain the details.

IT'S HAPPENING!!!! IT'S ACTUALLY HAPPENING!!!! pic.twitter.com/i5PCBBWLYy

— RyanGoldfish (@GoldfishRL) August 19, 2021

Rocket Science explains Rocket League moving to Unreal Engine 5

Rocket Science is a popular Rocket League YouTube channel that explains the ins and outs of the game’s physics and game design. Its owner, HalfwayDead, has often shown how certain mechanics and physics work the way they do and why. In a 25-minute long video, the Rocket League physics expert broke down what exactly an upgrade for Unreal Engine 5 is useful for and what we can expect if and when it happens.

Most simply, an upgrade to Unreal Engine 5 may help with performance, according to HalfwayDead. However, he noted that performance is not the most likely reason for Psyonix wanting to make the change. After all, Rocket League runs perfectly fine on many different setups, including low-budget ones. Rather, a move to Unreal 5 helps future-proofing the game and its architecture.

“The Unreal Engine 5 is gonna give the developers more modern tools and features that are integrated into the engine, with support from Epic,” HalfwayDead said in the video.

He went on to add that the change may lead to better graphics and new features that otherwise wouldn’t be possible to implement. Unreal Engine 5 may also help with new technologies from NVIDIA and AMD, because they often have direct plugins for the engine, the YouTuber noted.

There are many other improvements possible with an upgrade to Unreal Engine 5. HalfwayDead also mentioned an update to the netcode, which, for example, is useful to create more consistent touches of the ball. He also brought up the possibility of a more optimized UI and better shadow distance.

The tradeoffs

Nevertheless, with a new engine come new difficulties. Rocket League is a heavily physics-based game. Players have thousands and thousands of hours of training based on how the game interacts. An engine upgrade may lead to changes in the game’s mechanics. Most notably, HalfwayDead noted, is the way the game calculates physics right now and how they could be improved. The game currently makes a physics timestep for every eight milliseconds.

“Between those physics steps, there is no simulation happening,” HalfwayDead says. “Which means you could basically tunnel through an object if you get from one side to the other within eight milliseconds.”

Eight milliseconds is enough for the game to function and feel just fine. But it does lead to some unnatural behavior when one takes a closer look. Rocket League does not have continuous collision detection, which could lead to a bounce or collision that in the real world would have happened sooner. Experienced players will be used to these bounces and, for example, the way the ball interacts with the wall curve. But with continuous collision, the ball could bounce slightly differently. After thousands of hours of gameplay, that difference will be noticeable. Regardless of the physics being slightly unrealistic in Unreal Engine 3, changing those physics will likely require an uncomfortable adjustment for many players and will likely be seen as controversial.

Of course, it is unknown what Psyonix is planning with the upgrade. They may keep the same settings, or they may use the opportunity to implement more accurate physics.

Another tradeoff is the use of current mods, such as Gifyourgame and Bakkesmod. There are many mods and plugins available through a mod called Bakkesmod. This allows players to equip any item they want, install plugins for extra customization, custom map loading, fun settings and more. Bakkesmod is an extremely popular mod for PC players, but with Unreal Engine 5, the difference will be so large that it will likely take a long time to make it compatible.

Rocket League transitioning to UE5 might be one of the biggest game transition ventures ever in the history of games. The amount of content they have to reimagine in UE5 from the ground up to transfer player inventories and rebuild maps/models, etc is scary

— SSG Lethamyr (@Lethamyr_RL) August 20, 2021

Ultimately, Psyonix said it is a long-term project. Pro player and content creator Treyven “Lethamyr” Robitaille notes that many assets will have to be built up from the ground. While HalfwayDead is not sure about that, he does acknowledge that Psyonix has a lot of work ahead of them.