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Orange Box (engine branch)

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Source 2007Source 2009Source Multiplayer The Source 2007 engine branch, also known as The Orange Box engine branch, was released in Oct 10, 2007 with the release of The Orange Box The Orange Box (Half-Life 2: Episode Two, Portal, and Team Fortress 2), succeeding the Source 2006 Source 2006 engine branch. Half-Life 2 and Half-Life 2: Episode One were also ported to Source 2007 only on consoles (until 2010 when the PC port of Half-Life 2 and Half-Life 2: Episode One were later ported to 2009 branch).

It was maintained side-by-side with the Left 4 Dead engine branch Left 4 Dead engine branch, which, around this time, all first-party Source 2006 (except Half-Life: Source) and Source 2007 games were upgraded to Source 2009 (for singleplayer games) and Source Multiplayer (for multiplayer games) throughout until July 2010, when it was obsoleted by the release of the Alien Swarm engine branch Alien Swarm engine branch. Despite this, the Source 2013 Singleplayer and Source 2013 Multiplayer branches were released in 2013 as more direct upgrades for these games.

In an attempt to stop Bunnyhopping, Valve updated the movement system to cap the forward move speed, inadvertently creating Accelerated Back Hopping. This branch also introduced few bugs noticeable in Half-Life 2 (and it's episodes), such as the Dropship container gun no longer rotates, and thus unable to shoot unless you stand in the front of the gun, which significantly make the battle on the Sandtraps chapter much easier.

In May - June 2010, all first-party Source 2006 and Source 2007 games for PC (except for Half-Life: Source, Half-Life Deathmatch: Source, and Half-Life 2: Lost Coast) were upgraded to Source 2009, which adds support for macOS, aswell introducing achievements for PC/Mac version of Half-Life 2 and Half-Life 2: Episode One. Optionally, achievements are also supported on third-party mods.

The Orange Box builds on the original Half-Life 2 branch, requiring its content installed to work.


There are three Orange Box branches, referred to in the SDK Launcher as Source 2007 Source 2007, Source 2009 Source 2009, and Source Multiplayer Source Multiplayer. The 2009 and MP branches do not have a different feature set, but they are incompatible with 2007 due to various under-the-hood changes (which include a different SteamID scheme and Mac OS X compatibility).


New since the Source 2006 Source 2006 engine branch are:

Source 2007 2007

Logic, rendering and audio have been threaded for performance gains in multi-core environments.
Soft particles
An all-new, artist-driven particle system, replacing the old hard-coded particle system.
Shadow mapping
Special dynamic lights such as the player's flashlight can now cast high-quality dynamic shadows.
Improved High Dynamic Range rendering
Remade HDR tonemapping that better fits outdoor scenes.[1]
Motion blur
Cheap and simple camera motion blur.[1]
Hardware Morph (HWM) flexes and Wrinkle maps
A new, powerful facial animation system, with support for textures that add fine wrinkling detail to the face during flex animation.
Conditional statements
New conditional statements for use in materials to optimize them for lower-end machines.
Phongwarp textures and other Phong improvements
Source's phong shading, introduced in Source 2006 Source 2006, has been upgraded with additional features such as reflection tinting, albedo tinting, phongwarp textures, and more.
Self-shadowing bump maps
A special, cheaper kind of bump map for brush shaders with baked in shadows to give the illusion of a self-shadowing surface.
Automatic displacement texturing
Mitigates texture stretching across displacement surfaces.
Alpha to coverage
Vector-like edges to raster images, fast.
Flowing emissive textures for models
Advanced flowing emission for VertexLitGeneric, notably used on the Vortigaunts in Half-Life 2: Episode Two Half-Life 2: Episode Two
Fresnel for specular reflections and self-illumination on models
On VertexLitGeneric, $envmap and $selfillum have new parameters to enable shading with the Fresnel effect.
Cinematic Physics
Baked physics animations that are rendered offline and brought into the engine for playback with minimal performance cost.
A new entity to be placed in large open areas with unbroken visibility, reducing compile times.
Bink video
Replaces the old AVI file format which was used on game intros.
Maplist Thumbnails
A console-oriented server browser UI.
Xbox 360 Xbox 360 and basic PlayStation 3 PlayStation 3 support
Of little use to modders, needless to say! Aside from that, native support for the Xbox 360 controller when played on PC has been added, alongside with XInput support.
The PlayStation 3 version was ported by EA (Electronic Arts) due to the complexity of the hardware at the time. This result in the game running worse than the Xbox 360 counterpart.

Source 2009Source Multiplayer 2009/MP

macOS Mac OS X support
Supported since 2010 engine update. The engine can now run on Mac. However, Mac support outside of official games may be spotty.
Furthermore, newer version of macOS since 10.15 (Catalina) no longer support all 32-bit apps and games in general (which also includes every single Source engine games that are complied for 32-bit only).
QuickTime video (MOV) (only in macOS)
Replaces BINK video and only used on macOS macOS systems. Some games may also support Bink video on macOS macOS.
Particle system adjustments
Particles can now render blobs and models.
Not available in subsequent branches (removed in Source 2013 Source 2013, and not ported upstream to Alien Swarm engine branch Alien Swarm engine branch).
Disable phys_bone_followers
phys_bone_followers can now be disabled on dynamic props for performance gains and lower entity counts.

Source 2013 2013

Source 2013 Source 2013 (both SP and MP) has its own page.


Most games using this branch (except Console version of those games) were upgraded to the Source 2013 Singleplayer Source 2013 Singleplayer or Source 2013 Multiplayer Source 2013 Multiplayer branches when those released. Nevertheless, gamecode for the 2007 branch is included in the now-deprecated Source SDK app.

Source 2007



Source 2009


  • 2009 Zeno Clash Zeno Clash
  • 2009 Vindictus Vindictus[confirm]
    • Heavily modified, and uses proprietary file format to store game files. Also support Direct3D (DirectX) 11.
  • 2011 Postal III Postal III
    • Added PhysX physics engine for certain cloth models. Also contains a modified MDL format, unique scripting language (Postal3Script), a system for using env_sprites for trees and hair, as well as a unique implementation of Nextbots. A former developer described it as such[1]:
"We messed it up from the start. In the later stages we were trying to upgrade to the latest source version [Source 2009] with some luck – that was part of the multiplayer effort. But we messed a lot to a source engine core, we messed with client/server architecture. It is a miracle the game was working at all."

Source MP



  1. Valve GDC 2008: Post Processing in The Orange Box
  2. Interview with a Trashmasters dev who wished to remain anonymous