Rubikon

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Rubikon mascot used in Sergey Migdalskiy's lecture at GDC 2014.

Rubikon is Valve's custom CPU based^[1] physics engine used in Source 2. It replaces Havok, which is the main provider of physics for Source engine games. The Rubikon physics engine is developed by Dirk Gregorius.

Valve switched from Havok to Rubikon in order to reduce licensing cost.

Todo: Describe the Ragnarok engine.^[2]

Related Physics Engines

Box3D, used in  s&box, started as a fork of Dirk Gregorius' personal, non-Valve version of Rubikon (dubbed "Rubikon-Lite"), and was then heavily modified to use mainly Box2D code; It still retains some Rubikon-Lite code in its convex hull generation and some of its collision algorithms.^[3]

External links

• Rubikon at GDC 2014 — Valve's Physics for Game Programmers.
• Document from GDC 2014 — Sergiy Migdalskiy Debugging Techniques.pdf (Archived version).

References

1. Dirk Gregorius (March 10, 2015). "Rubikon : Valve's physics engine for Source 2". Real-Time Physics Simulation Forum. Retrieved on September 11, 2026.  2. Erin Catto (Jun 30, 2026). "Announcing Box3D". Box2D. Retrieved on September 11, 2026.  3. gvarados (@gvarados) (August 3, 2024). "S&box has a new Physics Engine". X (Twitter). Retrieved on September 11, 2026.