GGPO Rollback Netcode Goes Open Source
On October 9, 2019, Tony Cannon released GGPO under the MIT license, removing the licensing friction that had limited its adoption and helping cement rollback as the fighting game industry's netcode standard.
GGPO, the rollback netcode middleware credited with popularizing rollback specifically for fighting games, was released as open source under the MIT license on October 9, 2019 — an announcement made directly by creator Tony Cannon via Twitter.
From a personal project to an industry-shaping tool
Cannon — co-founder of the fighting-game community site Shoryuken and the Evolution Championship Series (Evo) — built GGPO out of frustration with the online play quality of a 2006 fighting game re-release, releasing the first version later that same year. Games including Skullgirls and Street Fighter III: 3rd Strike Online Edition went on to use it, though notably, Street Fighter IV — one of the decade’s biggest fighting game releases — shipped without it.
What open-sourcing actually changed
Before this release, using GGPO commercially generally meant a custom licensing arrangement directly with Cannon — a real, if not enormous, barrier to adoption compared to a tool any developer could simply pull in and use freely. Releasing it under the MIT license — a highly permissive open-source license — removed that friction entirely: any developer, on any project, commercial or not, could now integrate GGPO’s rollback implementation without negotiating terms first.
Why the timing mattered
By 2019, rollback had already become the technique competitive fighting game communities most wanted from new releases, with delay-based netcode increasingly viewed as a dealbreaker for serious competitive play. Open-sourcing GGPO at this specific moment gave smaller and independent developers — who might never have pursued a custom licensing deal — a straightforward path to implementing the same rollback approach larger studios were already using, likely accelerating rollback’s shift from “a differentiator some games have” to “the expected baseline every serious fighting game needs.”
Why this release is a natural bookend to GGPO’s origin story
GGPO began as one developer’s frustrated response to bad netcode in a single game; ending its proprietary licensing model entirely, more than a decade later, extended that same original motivation — better online play for the fighting game community — to every developer who might benefit from it, not just those able to negotiate a licensing deal directly with its creator.
Sources: GGPO — Wikipedia, Good news everyone! GGPO rollback netcode is now free to use — EventHubs