The foundation of
Ultima Online emulation
For over two decades, RunUO has powered virtual worlds with enterprise-grade reliability. Trusted by thousands of servers and 500,000+ players worldwide.
Built for reliability
and performance
Two decades of continuous innovation and refinement.
Enterprise-grade stability you can trust.
Robust
Architecture
Enterprise-grade server core engineered for optimal performance. Designed to handle high-volume traffic reliably.
Developer
Experience
Native C# scripting with comprehensive APIs. Build custom features with familiar tools and patterns.
Production
Ready
Thousands of servers worldwide. Half a million players trust RunUO's stability.
23 years
of innovation
The remarkable journey that established
the foundation of virtual world development
Foundation
Krrios & Ryan launch RunUO with an innovative walking engine that revolutionizes UO emulation.
Growth
Widespread adoption across hundreds of servers. The community flourishes worldwide.
Maturity
Platform maturity achieved. Professional-grade stability with enterprise features.
Legacy
Still leading the industry. The trusted platform that continues to evolve.
Where projects take shape
Join thousands of developers and server administrators who trust RunUO to power their virtual worlds. Your next project starts here.
Industry Standard
The most trusted and widely adopted UO server platform, setting the standard for over two decades.
Active Community
Thousands of developers, administrators, and players contributing to a thriving ecosystem.
Open Source
Free, open-source platform with transparent development and community-driven improvements.