Formal development of Rocket League began around 2013.
Psyonix developed Rocket League as a sequel to its 2008 PlayStation 3 game, Supersonic Acrobatic Battle-Cars. The earlier title established the basic idea of rocket-powered vehicles playing soccer, but it attracted fewer players than expected. Psyonix retained the concept and later used feedback from its small, dedicated audience to shape the sequel.
Full development started around 2013 and took roughly two years, with a budget of under $2 million. The team improved the frame rate from 30 to 60 frames per second, made the gameplay more approachable, strengthened online infrastructure, and refined the physics. Psyonix also tested prototypes and attempted to pitch the concept before committing to development.
The date can be confused with other milestones. A sequel was discussed as early as 2011, Rocket League was announced in February 2014, and the finished game launched on July 7, 2015. Thus, 2013 refers specifically to the start of formal full development, not the first prototype or public release.