SEGA delivers global crossplay in Sonic Racing: CrossWorlds with Epic Online Services
Since the release of the original Sonic the Hedgehog in 1991, SEGA’s iconic blue hedgehog has grown into one of the most recognizable and enduring franchises in gaming history.
Released in September 2025, Sonic Racing: CrossWorlds marked another critical and commercial milestone for the series—offering cross-platform multiplayer experience between PC and console platforms.
Delivering that experience at a global scale was a significant technical undertaking, requiring reliable crossplay, consistent performance, and rapid responsiveness across a wide range of platforms and network conditions.
In this developer Q&A, the Sonic Racing: CrossWorlds development team shares how they used Epic Online Services to take on those challenges and bring large-scale online racing to players worldwide.
Released in September 2025, Sonic Racing: CrossWorlds marked another critical and commercial milestone for the series—offering cross-platform multiplayer experience between PC and console platforms.
Delivering that experience at a global scale was a significant technical undertaking, requiring reliable crossplay, consistent performance, and rapid responsiveness across a wide range of platforms and network conditions.
In this developer Q&A, the Sonic Racing: CrossWorlds development team shares how they used Epic Online Services to take on those challenges and bring large-scale online racing to players worldwide.
Can you tell us about the background of the Sonic Racing: CrossWorlds development team, and how that experience shaped your approach to online multiplayer?
Over the course of 40 years, SEGA developed a wide range of arcade game titles—such as Outrun, Daytona USA, and SEGA Rally Championship—and continually evolved the player experience.
For the racing genre in particular, over many years we have refined our own proprietary, P2P-based networking system optimized for synchronization control and real-time communications that enables low-latency multiplayer. The foundational technologies and know-how built up through more than 20 years of operating arcade games with online functionality are still being inherited and refined among engineers today.
With these highly experienced members at the core of our team, we took on the challenge of developing global cross-platform multiplayer for Sonic Racing: CrossWorlds.
What new technical challenges emerged when extending your existing P2P approach to a fully global, cross-platform environment?
On one hand, the technical staff had experience implementing an in-house P2P communication system, with a proven track record of providing a smooth gaming experience in Japan and Asia’s network environments.
On the other hand, to implement Sonic Racing: CrossWorlds, we faced new technical challenges. These included crossplay between PC and console platforms, developing communication APIs that are compatible with network environments throughout the world, and server scalability that can support a global user base.
What led you to choose Epic Online Services to tackle those challenges?
EOS has three traits that we determined made it the right tool for the job.
The first trait is a cross-platform compatible SDK. The SDK is compatible with a wide range of consoles, providing an environment that can run immediately. Because the SDK allows crossplay, it both resolves the technical challenge and allows quick creation of a playable ROM where iterative improvements can be made for the online race experience.
The second trait is that EOS is built with scalability in mind. As seen with Fortnite, Epic runs on server infrastructure capable of supporting millions of players worldwide. This trusted and tested infrastructure offers significant advantages both in terms of addressing server scalability and ensuring reliable operation even after release.
The third trait is the adaptability of the network API. EOS’ API supports P2P communication that our team at SEGA have traditionally developed. Further, it considers firewalls and Network Address Translations (NATs) appropriately and automatically decides the optimal method of connection.
Our use of Unreal Engine 5, which comes with core online features, also let us efficiently integrate EOS. By having EOS handle the various networking functions and providing crossplay at proven scale, we believed we could focus exclusively on improving game quality, instead of focusing on the details of technical implementation.
What drove you to choose Unreal Engine for development on Sonic Racing: CrossWorlds?
Similarly with our choice of EOS, we required multi-platform deployment. We knew UE5 had strong cross-platform capabilities. And considering our team already had experience with Unreal Engine, the choice felt natural.
Of note, we were able to boost productivity through UE5’s plugins and editor extensions by developing in-house tools tailored to this project’s unique racetrack production workflow.
Validating network quality at a global scale must have been critical. What was your approach to iteration and testing for this?
During the development of Sonic Racing: CrossWorlds, we planned multiple stages of testing to stabilize network quality on a global scale, and iterated with the Plan-Do-Check-Act (PDCA) cycle of implementation, verification, and improvement.
We first accumulated results through internal testing. Starting domestically and in office, we continued with tests spanning our Japan, Europe, and US offices, and then we reached the Closed Network Test (CNT), the first opportunity allowing our customers to play in their own environment.
How did the CNT go? What did it reveal about real-world player behavior and network conditions?
In the preparatory phase prior to the test, we shared our CNT estimated player count with Epic, and we received support with server scaling as well as monitoring during the test. We are so thankful to receive support from Epic before facing our first large-scale test.
As a result, we achieved the milestone of 43,000 downloads worldwide and one million online play sessions. This exceeded our expectation of matchmaking consistently supporting around 15,000 players.
In addition, we collected gameplay data and conducted a survey. This allowed us to analyze quantitative data such as the user-to-user latency, packet loss , and the percentage of connections being routed through relay servers, along with the feedback gathered from players through the survey.
Because these results aligned with the predictions we made stemming from historical online play data we gathered from prior arcade titles, it increased our confidence going forward.
As a result of the prediction being close to the result, 95% of post-CNT questionnaire respondents reported that the network was stable. The data and feedback was a key component to reconcile the differences between our projections and the actual results as we moved toward our next major milestone, the Open Network Test (ONT).
How did the data and feedback from CNT directly inform the technical focus and priorities of the ONT?
For us, the ONT was the most important event for conducting crossplay network tests on a global scale and performing final adjustments before release. Here, we introduce our CNT analysis results and the technical challenges we faced along with our solutions under a cross-platform environment.
1. Tuning predictive behavior in high-latency environments:
In Sonic Racing: CrossWorlds, the online player’s behavior is realized through a combination of player actions and a predictive algorithm. While an opponent’s vehicle behavior is corrected through prediction, we gradually adjust it towards the opponent’s vehicle behavior as soon as their input packets are received. By combining these in real time, we reduce the feel of lag by continuously correcting the movement. Strengthening the prediction allows compatibility with higher latency, but also increases the gap in the opponent’s behavior. We adjusted the degree of prediction in low, medium, and high latency based on the CNT data.2. Reducing the frequency of communication for a natural play experience between differing frame rates:
Sonic Racing: CrossWorlds performs at 30 FPS or 60 FPS depending on the specs of various platforms. When differing frame rates match together, if we send and receive packets based on the game’s frame rate, the side with lower frame rate won’t be able to keep up with packet processing. By adjusting the packet processing rate to be independent of the game’s frame rate, we solved this issue alongside vehicle predictive behavior.What impact did resolving these challenges have on stability, scale, and player experience during the ONT?
We believe resolving these contributed to the substantial accomplishment of the ONT’s one million downloads and 10 million play sessions within four days.
As you moved from large-scale testing toward launch, what final adjustments were necessary to ensure consistent connectivity across diverse network environments?
To identify the communication errors of the ONT, we had remote employees conduct additional tests with standard internet connections. This verification confirmed that in certain network environments, when the NAT type switches, connectivity issues can occur over P2P or LAN routes. As a result, we switched to the “ForceRelays” mode, which restricts the communication path to relay servers. Although this comes with a trade-off against latency optimization, we believe being able to flexibly switch EOS SDK’s operating modes is a major advantage.
How did Sonic Racing: CrossWorlds perform at launch, both in terms of player reception and cross-platform engagement?
Through solving these technical challenges, Sonic Racing: CrossWorlds successfully reached its launch. As for results, we received a Metacritic user score of 9.0, and a critic Metascore of 82.
Steam reviews were overwhelmingly positive, and we passed one million sales. A Switch 2 version was released, so now Sonic Racing: CrossWorlds can be played on all console platforms.
As for crossplay, the barriers between platforms were removed, and we were able to provide an environment where players can play across varying platforms.
From our analytics, of two-player squads, 26% are on different platforms.
Looking back, how did Epic Online Services support your goals?
We are immensely satisfied with being able to achieve what we had hoped with EOS. The careful support from Epic's team was a tremendous help.
For development teams like ours striving for worldwide expansion, EOS serves as an invaluable service.
For more information on Sonic Racing: CrossWorlds, visit the official website or its page on the Epic Games Store.
To dig deeper into Epic Online Services P2P services, see NAT P2P Documentation and our P2P How-to Guide.