Most of Portal's soundtrack is non-lyrical ambient music composed by Kelly Bailey and Mike Morasky, somewhat dark and mysterious to match the mood of the environments. It was released in part on The Orange Box Original Soundtrack, which includes both GLaDOS's in-game rendition and Jonathan Coulton's vocal mix of the closing credits song, "Still Alive".
"Still Alive" was written by Jonathan Coulton and sung by Ellen McLain as the GLaDOS character. A brief instrumental version of Still Alive is played in an uptempo Latin style over radios in-game. Erik Wolpaw noted that Coulton was invited to Valve a year before the release of Portal, before it was clear where Coulton would contribute. Wolpaw stated: "Once Kim [Swift] and I met with him, it quickly became apparent that he had the perfect sensibility to write a song for GLaDOS." The use of the song over the closing credits was based on a similar concept from the game God Hand, one of Wolpaw's favorite titles. The song was released as a free downloadable song for the music video game Rock Band on April 1, 2008.
Using an appropriate program, it is possible to extract all audio tracks heard in-game from the
portal_pak_dir.vpk archive file. Portal's soundtrack was also included in the game directory of both the full and demo Audiosurf releases on Steam as part of Audiosurf's The Orange Box Soundtrack. Additionally, on October 30, 2012, it was released as the fourth volume in a four-disc retail release, Portal 2: Songs To Test By (Collector's Edition), featuring music from both games. On September 24, 2014, the soundtrack was made available as free DLC to all owners of the game on Steam.
* = not present in a given soundtrack.
|The Orange Box OST #||Game #||OST (Steam DLC) #||Track title||Filename||Time||Level location||Comments|
|*||01||02||Taste of Blood||
||3:06||Test Chamber 02: Shortly before obtaining the blue Portal Gun.||The title is a reference to GLaDOS' description of the Aperture Science Material Emancipation Grill in Test Chamber 02.|
|*||02, 09||05||Procedural Jiggle Bone||
||4:34||Also plays in the menu screen.|
|14||03, 06||04||Self Esteem Fund||
||3:30||The title is a reference to a sentence said by GLaDOS in Test Chamber 15.|
|13||04||01||Subject Name Here||
||1:44||Test Chamber 11: When riding the Aperture Science Unstationary Scaffold leading to the Dual Portal Device podium.||The title is a reference to a sentence said by GLaDOS in Test Chamber 06.|
|*||05, 08||03||Android Hell||
||3:45|| Test Chamber 13: When entering the main room. (first instance)
Test Chamber 18: When entering the large room full of Aperture Science Sentry Turrets. (second instance)
|The title is a reference to a sentence said by GLaDOS at the end of Test Chamber 16.|
|*||07||06||No Cake For You||
||4:05||Test Chamber 16: When entering the first Ratman den.|
|15||10||07||4000 Degrees Kelvin||
||1:01||Test Chamber 19: When approaching the fire pit.||Also plays during the second half of the Portal announcement trailer. The title is a reference to a sentence said by GLaDOS at the end of Test Chamber 19. This track features the "Beat 42", "Beat 43", and "Beat 46" audio samples included in Sony's Methods of Mayhem: Industrial Toolkit sample album.|
|16||11||08||Stop What You Are Doing||
||3:57||Escape: After escaping the fire pit.||The title is a reference to a sentence said by GLaDOS in the maintenance areas of Aperture Science.|
||4:21||Escape: Just before and during the first encounter with the Rocket Turret.||The title is a reference to a sentence said by GLaDOS when Chell escapes from the fire pit as well as the Party Escort Bot.|
|17||13||10||You're Not A Good Person||
||1:22||Escape: During the massive Sentry Turret ambush.||The title is a reference to a sentence said by GLaDOS in the maintenance areas of Aperture Science.|
|18||14||11||You Can't Escape, You Know||
||6:14||Escape: During the boss fight with GLaDOS.||The title references to a sentence said by GLaDOS in the maintenance areas of Aperture Science, though with a slight change.|
|19||*||13||Still Alive (J.C. Version)||-||2:56||Credits Remix from The Orange Box Original Soundtrack.||Version of the song performed by Jonathan Coulton.|
|*||*||*||Still Alive (Aperture Science Radio version)||
||0:21 (loops)||Radios found throughout the game.||Easy listening / Latin instrumental version of Still Alive played from the radio prop. The in-game closed captions describes the track as "[Peppy Music]". In the early stages of the game's production (2005), the stock merengue instrumental "Mirame" was used as a placeholder. It was first used by Valve in the Counter-Strike: Source map Inferno, and is also featured in Counter-Strike: Global Offensive. Its other appearances include Aperture Hand Lab and Valve's promotional video "Steam Remote Play Together".|
- Coulton, Jonathan (October 15, 2007). Portal: The Skinny. Jonathan Coulton's blog. Retrieved on November 1, 2007.
- Walker, John (October 31, 2007). RPS Interview: Valve's Erik Wolpaw. Rock, Paper, Shotgun. Retrieved on October 31, 2007.
- Turi, Tim (2012-09-01). Chell Almost Married A Turret In Portal 2. Game Informer. Retrieved on 2012-09-06.
- Baptiste, Sean (2008-02-21). Valve Party at GDC + Special Preview of an Upcoming DLC Song. Harmonix. Archived from the original on 2008-02-25. Retrieved on 2008-02-21.
- Baptiste, Sean. DLC April 1st! Huge success!. Rockband.com forums. Retrieved on 2008-03-31.
- Faylor, Chris (2008-03-31). 'Still Alive' Hits Rock Band X360 Tomorrow for Free, PlayStation 3 Edition Due Mid-April. Shacknews. Retrieved on 2008-03-31.
- Hinkle, David (2012-09-24). Portal 2: Songs to Test By (Collectors Edition) out on Oct. 30. Joystiq. Retrieved on 2012-09-24.