Source 2 Engine

The Source 2 Engine is Valve Corporation's proprietary game engine that powers Counter-Strike 2. It is the successor to the original Source engine that powered CS:GO, Half-Life 2, and many other Valve titles.

Overview

Source 2 was first publicly shown with Dota 2 Reborn in 2015 and was later used for Half-Life: Alyx (2020). Counter-Strike 2 (2023) brought Source 2 to the Counter-Strike franchise, enabling significant technical improvements over the Source 1-based CS:GO.

Key Improvements for CS2

Rendering

Physically Based Rendering (PBR) — More realistic lighting and material responses
Dynamic lighting — Real-time light sources that interact with the environment
Improved particle effects — More detailed smoke, fire, and explosion effects
Higher texture resolution — Sharper, more detailed surfaces
Better reflections — More accurate environmental reflections

Networking

Sub-Tick System — Actions processed at the precise moment they occur, not at tick boundaries
Improved hit registration — More accurate server-side detection
Better interpolation — Smoother movement rendering between updates

Physics

Enhanced ragdolls — More realistic player and object physics
Volumetric smoke — 3D smoke that reacts to lighting, bullets, and explosions
Responsive smokes — HE grenades and gunfire can temporarily disperse smokes
Improved grenade physics — More predictable bounce and trajectory behavior

Map Tooling

Hammer 2.0 — Updated map editor with modernized workflow
Faster compile times — Maps build more quickly
Sub-object editing — More granular control over map elements
Improved lighting baking — Better quality lightmaps with faster generation

Audio

Reworked 3D audio — More accurate spatial sound positioning
Improved HRTF — Better headphone-based directional audio
Dynamic sound propagation — Sound travels realistically through map geometry

System Requirements Impact

Source 2 generally requires more powerful hardware than Source 1:

Higher GPU requirements for PBR rendering
More VRAM usage for higher-resolution textures
Increased CPU load for improved physics and networking
CS2 minimum requirements are notably higher than CS:GO's

Comparison with Source 1

Feature	Source 1 (CS:GO)	Source 2 (CS2)
Rendering	Pre-baked lighting	Dynamic PBR lighting
Smoke grenades	2D sprite-based	3D volumetric, reactive
Tick system	Fixed tick rate (64/128 Hz)	Sub-tick precision
Map editor	Hammer 1.0	Hammer 2.0
Physics	Havok (limited)	Enhanced physics system
Audio	Basic 3D audio	Full HRTF spatial audio

Other Source 2 Games

Dota 2 — Ported to Source 2 in 2015 (Reborn update)
Half-Life: Alyx — VR title built on Source 2 (2020)
Counter-Strike 2 — Latest Source 2 game (2023)