Star Engine

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Star Engine Logo

Star Engine is the video game engine used by Star Citizen and Squadron 42.

Star Engine aims among others to simulate a very large-scale universe, seamlessly and without any loading screens or invisible walls despite being massively multiplayer.

Development

Star Engine is a heavily refactored version of CryEngine 3 from Crytek used since the first in-engine video released at the start of the Crowdfunding campaign. More specifically, the last CryEngine update integrated into Star Citizen's code was patch 3.8. This heavily modified version has been internally named Star Engine since September 2016 at the latest, before moving to Amazon Lumberyard.

On 2016-12-23, CIG announced with the release of Star Citizen Alpha 2.6.0 its move to Amazon Lumberyard game-engine, which is also based on CryEngine 3.8, in order to utilize the integrated Amazon Web Services (AWS) and Cloud-Computing features "to support next generation online gaming" . Since then, large portions of the engine have been rewritten internally by CIG, including rendering, networking, persistence and simulation technologies. It can no longer be accurately described as a specific Lumberyard version.

The StarEngine development and support is driven internally within Cloud Imperium Games with some of former Crytek employees supervising the project. A lot of the work on it is done in the Frankfurt studio.

The term "Star Engine" was officially used for the first time during the presentation "The Future of Gaming: StarEngine" at CitizenCon 2953. The trademark was filed a few days later by CIG on October 26, 2023.

Features

Although CIG is very open about their development process, not all details on internal processes and work on the engine are released to the public. The following list contains features that are described in interviews, Monthly Reports or dev comments. The names can differ from the actual name internally used and the feature funtionality should always be considered as not fully accurate. Additionally, some are already integrated CryEngine 3.8 and/or Lumberyard features - for a list see  CryEngine

Here's a list of features added by CIG since CryEngine 3.8.

Notable Tech

• Large World (64bit world space coordinates)
• Object Container Streaming
• Mega Map
• Zone System
• Local Physics Grids
• Room System
• Camera Relative Rendering
• Procedurally Generated Planets
• PBR (Physically Based Rendering)
• The Sun as a physical object (possibility of Binary Star Systems or exploding ships in orbit casting light to the planet surface)
• StarScript (formerly Subsumption AI)
• Unified First- & Third-Person animations
• Unique Global Entity ID
• Generic Instance Manager
• Universe Simulator
• Persistence (Player Info Server, Presence Server, HUB Server and Player Persistence)
• Persistent Entity Streaming
• Replication layer
• Entity Graph
• Item Port System
• Server meshing
• "Grabby Hands" - now integrated into the Cargo system and Loot system, initial system for grabbing and moving objects (e.g. cargo) and initially set to be released in the (later delayed) Astro Arena or SATABall FPS game mode
• Multi-LayerBlend - character shader tech
• iPredictor (movement prediction) system
• Diffusion (cloud-oriented back-end service architecture)

Rendering

Object space shader damage

Allows 4 different types of damage to be permanently inflicted on ships, including cutting holes, and blended seamlessly into the base shading.

Real time environment-probe capture and compression

Avoids needing to bake probes in space and on planets.

Image based lens flares

Use entire source image to simulate 4 different physically based lens distortions per color channel on up to 20 individual elements

Physically based bloom

Wide exponential kernel based purely on light intensity.

Human eye exposure simulation

Capture histogram of light intensity from both screen and surroundings, isolate range of light we intend to focus on, simulate both pupil and photo-pigment reactions for quick and slow reactions.

Major improvements to planar lights

Far more physical basis now which results in major quality improvements.

Intelligent mesh-merging system

Repeatedly searches for best bang-for-buck mesh merge opportunity in a scene until we hit a memory limit.

Upgraded volumetric fog

E.g.: support for planar lights, light-boxes, enviroment-probe priority sorting.

Major upgrade to shadow pool system

All lights share one giant pool for better dynamic resolution scaling, shadows can be cached between frames for better performance.

Render target pooling

Shares memory between internal textures used in the renderer to vastly reduce VRAM usage.

Render to texture pipeline

Ability to render secondary viewports with full or limited feature set to then be used as textures in the primary scene, e.g.: video comms or holograms.

Tiled lighting upgrades

Use rasterization light culling for greater efficiency, particle support.

Density based LOD algorithm

LODs change based on polygon density to ensure consistent appearance, less artist intervention, and promote more optimal art assets with fewer sub-pixel polygons.

GGX normal map filtering

gloss adjusted in mip-chain to best fit of our GGX lighting model to give the same results as super sampled normals.

Camera relative rendering

Allows 64-bit world without incurring any rendering performance hit by maintaining 32-bit precision for rendering.

GPU Particle System

Built from the ground up for efficiency, distinct from Lumberyards and CryEngine's GPU particle systems.

Various improvements to transparency sorting

Generalized system, allow depth of field and motion blur to not effect nearby in-focus objects, order independent transparency for specific shaders such as hair.

Artist friendly profiler

Captures statistics per art-team, and per area of the level allowing accurate breakdowns and quick diagnosing of performance issues.

Physically based atmospheric scattering

Hierarchical object management

Efficient searches and culling, local coordinate frames for things like ships inside ships on planets which are rotating etc.

High Dynamic Range

Gen12 renderer

it improves performance by reducing CPU workload and optimizing core usage through better management of the render thread.

Tech included in Star Citizen Alpha 4.8.0

• P4K System - improved data handling system
• Planetary Rotation
• Temporal Supersampling (TSAA) - previously rendered frames are used to improve the anti-aliasing results on the new frame
• Improved Screen Space Directional Occlusion (SSDO)
• New Filmic Tone Mapping Curve (ACES)
• PBR Glass - Glass (e.g. cockpits) can be rendered with phyiscs-based distortions, cracks, reflections and chromatic effects
• Terrain Occlusion & Shadowing
• Space Fog" (Gas Clouds in e.g. asteroid fields)
• New water - constantly in motion, reactive to wind and objects, be it footprints in puddles, rivers, lakes, oceans or hot tubs
• Cloud light shafts - 3D volumetric shadows from clouds as opposed to post effect
• Temporal Upscaling (DLSS, FSR and CIG TSR)
• Starhair
• Dynamic weather
• Dynamic Fire (partially)
• Ground fog - follows the terrain, fully integrated into the atmosphere, reduces the scattered light

Planned features (as of June 2026)

• Fully dynamic blood, sweat and tears
• Virtual Terrain Texturing
• Improved Scattering System
• Ray Traced Global Illumination
• Starcloth
• StarAudio
• Maelstrom - physically based destruction system.
• Genesis world builder

Tools & 3rd-Party Software

• Kythera - AI middleware
• Vulkan API - 3D graphics and compute API
• Wwise - Sound Engine
• FMOD - (deprecated) Sound Engine
• DataForge - Data management, Ship & Weapons balancing
• StoryForge - Dialogue and Conversations system, built upon DataForge
• VERS 3D (formerly known as PlanetEd) - Editor for creating planets
• System Layout Tool - Star system layout and design
• Room Management System - (deprecated) System for players to manage their hangars; now changed and integrated in Item Port System

Licensing

Star Engine is not available for sale nor licensing, in part for legal reasons related to existing agreements. Sean Tracy who has done that job at Crytek for a number of years said that this would require a 100% support a 100% of the time and he therefore hopes this won't happen at CIG and would oppose it as the game itself would massively suffer.

Trivia

• A typical Star Engine frame update has up to 64 hardware threads, 200 software threads, over 700 000 streamed-in entities on a server, millions of entities overall in the solar system, about 150 000 component updates.
• Any given frame has over 200 vehicles, thousands of actors, including new creatures, over 2 000 000 physical objects, over 100 000 objects generated per frame, many unique locations to explore in a gigantic seamless space.

List of Videos on the Star Engine

• Squadron 42 Trailer (2012)
• Gamers Nexus - Video Interview with Chris Roberts on Procedural Generation (2014)
• Gamers Nexus - Video Interview with Chris Roberts on Engine Architecture & Zoning Optimization (2015)
• Gamers Nexus - Video Interview with Chris Roberts on Instancing & Player Counts (2015)
• Chris Roberts on DX12 & Vulkan support (2015)
• Gamers Nexus - Video Interview with Chris Roberts on Character Tech, Weather System, & Engine Architecture (2016)
• Gamers Nexus - Video Interview with Sean Tracy on CPU thread management, Jobs System, Character Technology, Lighting, sun/planet movement, Authoring Tools & AI (2016)
• Gamers Nexus - Video Interview with Sean Tracy on Parallax Occlusion Mapping for Biomes edge-blending; Spring Tension and Inverse Kinematics for the Rover & Ships (2016)
• Gamers Nexus - Video Interview with Chris Roberts on Procedural Planets V2 (2016)
• Gamers Nexus - Video Interview with Sean Tracy on 64-bit Engine Tech & Procedural Edge Blending (2016)
• Gamers Nexus - CitizenCon 2016 PlanetEd tool (2016)
• CitizenCon 2953: Shaping the ‘Verse - The Future of StarEngine (2023)
• Star Citizen Live: Q&A StarEngine (2024)

See also

• Clive Johnson's comment on Star Engine modifications on top of CryEngine/Lumberyard