Developer commentary



The in-game Developer commentary, turned off by default, is intended to give players an insight into the development process of the game, as well as offering interesting information which might not have been obvious initially.

Valve introduced the feature in Lost Coast and later introduced it to Episode One, Episode Two, Portal, Left 4 Dead and Team Fortress 2.

Overview

 * To activate the icons, the player must enable developer commentary from the game menu. To listen to them in-game, the player is required to press the  key whilst the cross-hair is placed over the icon. The same key can be pressed again to stop the commentary. Distance from the icon is not a factor, as an icon can be activated from any proximity as long as it is visible.


 * The icons play recordings of Valve team members or voice actors, who talk about behind-the-scenes information, including how or why they made the map, an enemy, a character, or a storyline idea, what happened in the earlier iterations of the map or area, and in the voice actors' case, how they coped with the voice acting.


 * Sometimes, the nodes will take control of the player's camera in order to show different areas or techniques. An example of this can be seen in Lost Coast; the screen is separated down the center to show the difference in rendering with HDR enabled and disabled.


 * Activating a commentary node will temporarily disable the game's AI, thus rendering enemies useless; however, it does not stop music or sounds. To counter this, achievements cannot be achieved whilst in commentary mode, as it more or less makes the game easier.


 * On all Valve games, the co-founder, Gabe Newell, will make the introductory commentary, which usually consists of an explanation of how to control the nodes. At the end of some games, he will make the final commentary.

Half-Life 2: Lost Coast

 * Gabe Newell
 * Viktor Antonov
 * Randy Lundeen
 * Robin Walker
 * Gary McTaggart
 * Chris Green

Half-Life 2: Episode One

 * Gabe Newell
 * Greg Coomer
 * Jay Stelly
 * Marc Laidlaw
 * Bill Van Buren
 * Robin Walker
 * Matt T. Wood
 * Yahn Bernier
 * Jason Mitchell
 * Gary McTaggart
 * Ken Birdwell
 * Bill Fletcher
 * Matt Scott
 * Charlie Brown
 * Steve Bond
 * Randy Lundeen
 * Ted Backman
 * Keith Huggins
 * Scott Dalton
 * Brian Jacobson
 * Doug Wood
 * John Guthrie
 * John Morello
 * Dhabih Eng
 * Jim Dose
 * Jake Nicholson
 * Erik Wolpaw
 * Adrian Finol
 * Kelly Bailey
 * Jason Deakins
 * Gautam Babbar
 * Chris Green
 * Chet Faliszek
 * Ido Magal
 * Steve Kalning
 * Tom Leonard
 * Charlie Burgin
 * Laura Dubuk
 * Wade Schin
 * Erik Johnson
 * Jeff Hameluck
 * Lars Jensvold

Portal

 * Gabe Newell
 * Erik Wolpaw
 * Kim Swift
 * Jeep Barnett
 * Garret Rickey
 * Paul Graham
 * Greg Coomer
 * Bill Van Buren
 * Realm Lovejoy
 * Scott Dalton
 * Randy Lundeen
 * Jeremy Bennett
 * Robin Walker
 * Bay Raitt
 * Jason Brashill
 * Kerry Davis
 * David Kircher
 * Nick Maggiore
 * Chet Faliszek
 * Chris Chin
 * Lars Jensvold
 * Ellen McLain

Half-Life 2: Episode Two

 * Gabe Newell
 * Erik Johnson
 * Marc Laidlaw
 * Jeremy Bennett
 * Jason Mitchell
 * Gautam Babbar
 * Gray Horsfield
 * Chris Chin
 * Joe Han
 * Ted Backman
 * Joshua Weier
 * Steve Kalning
 * Elan Ruskin
 * Doug Wood
 * Erik Wolpaw
 * Chet Faliszek
 * Bill Van Buren
 * Chris Green
 * Randy Lundeen
 * Carl Uhlman
 * Jason Brashill
 * Dario Casali
 * Philip Co
 * John Morello
 * Danika Wright
 * John Guthrie
 * Matt Wright
 * Charlie Burgin
 * Jay Stelly
 * Ido Magal
 * Leslie Hall
 * Eric Strand
 * Jason Deakins
 * Kelly Bailey
 * Alex Vlachos
 * Vitaly Genkin
 * Gary McTaggart
 * Scott Dalton
 * Brian Jacobson
 * Ken Birdwell
 * Greg Coomer
 * Mike Durand
 * Aaron Seeler
 * Jason Ruyman
 * Matt Scott
 * Jason Holtman
 * Scott Lynch
 * Matt T. Wood
 * Doug Lombardi
 * Yahn Bernier
 * Julie Caldwell
 * Quintin Doroquez
 * Iestyn Bleasdale-Shepherd
 * John Cook
 * Kathy Gehrig
 * Steve McClure
 * Milton Ngan
 * Nick Maggiore
 * Lars Jensvold
 * Bryn Moslow
 * David Sawyer
 * Jess Cliffe
 * Jeff Sorenson
 * Jeff Lind
 * Chris Grinstead
 * Alfred Reynolds
 * Kerry Davis
 * Joe Demers
 * Jennifer Seeley
 * Doug Valente
 * Mike Blasczak
 * Mike Dunkel
 * David Speyrer
 * Chris Douglas
 * Dan LeFree
 * Richard Lord
 * Taylor Sherman
 * Marc Scaparro
 * Matt Rhoten
 * Greg Winkler
 * John McCaskey
 * Eric Twelker
 * Torsten Zabka
 * Martin Otten
 * Bill Fletcher
 * Derrick Birum
 * Tom Leonard
 * Steve Bond
 * Katie Engel
 * Jon Huisingh
 * Tim Larkin
 * Merle Dandridge

List of appearances

 * Half-Life 2: Lost Coast
 * Half-Life 2: Episode One
 * Portal
 * Half-Life 2: Episode Two