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|"Adrenaline Horror"||Primarily an action track, with some brass instruments.||We've Got Hostiles: When encountering the first Osprey in the game and a squad of HECU soldiers.|
|"Vague Voices"||A dark, quiet, yet strangely peaceful song. Reused for the Half-Life 2 soundtrack as "Black Mesa Inbound".||Black Mesa Inbound: During the tram ride to Sector C.|
|"Klaxon Beat"||A fast-paced techno beat.||Anomalous Materials: When Gordon Freeman acquires the HEV Suit.|
|"Space Ocean"||Reused for the Half-Life 2 soundtrack as "Echoes of a Resonance Cascade".||Played at the start of the chapter Unforeseen Consequences.|
|"Cavern Ambience"||This piece is commonly played when descending down elevators or shafts. Reused for the Half-Life 2 soundtrack as "Zero Point Energy Field".|| Unforeseen Consequences: While descending on a platform as Headcrabs come out of a vent above.|
|"Apprehensive Short"||One of the many short musical strings in the Half-Life soundtrack.|| Unforeseen Consequences: When seeing the Zombie in a chair in the dark room with the flashing light.|
Office Complex: While exiting the elevator and seeing a live wire blocking the path.
|"Bass String Short"||Another short musical string.|| Office Complex: In a booby-trapped room, with a boarded up exit and Headcrabs falling from the roof.|
Apprehension: Upon entering the freezer area.
|"Hurricane Strings"|| Reused for the Half-Life 2 soundtrack as "Neutrino Trap".||Office Complex: Within the freezer area.|
|"Diabolical Adrenaline Guitar"||A fast-paced, chase song. Reused for the Half-Life 2 soundtrack as "Lambda Core".||We've Got Hostiles: Immediately after the first encounter with the HECU, as well as during the chapter Surface Tension.|
|"Valve Theme (Long Version)"|| The theme of Valve Software. Reused for the Half-Life 2 soundtrack as "Hazardous Environments".||Surface Tension: During the cliffside area.|
|"Nepal Monastery"||This track plays when encountering Tentacles. Has a middle eastern feel to it.|| Blast Pit: When entering the Silo and hearing the tentacles for the first time.|
Surface Tension: When entering the realm of the tentacle in the sand.
|"Alien Shock"||This Song usually plays when facing Gargantuas. Remixed for the Half-Life 2 soundtrack as "Biozeminade Fragment".|| Power Up: First seeing the Gargantua.|
Surface Tension: Encountering the Gargantua in the parking garage.
|"Sirens In The Distance"||Remixed for the Half-Life 2 soundtrack as "Triple Entanglement".||On A Rail: Descending into the tunnels at the beginning of the chapter.|
|"Nuclear Mission Jam"||A techno song, sounds fitting for a hard task. Reused for the Half-Life 2 soundtrack as "Something Secret Steers Us".||At the start of the chapter Apprehension, as well as when picking up the Tau Cannon.|
|"Scared Confusion Short"|| Apprehension: While witnessing the first Ichthyosaur. Also while seeing a security guard get shot by Black Ops.|
|"Drums and Riffs"||The song's name is a good indicator of how it sounds, the music primarily being drums and guitar riffs. Reused for the Half-Life 2 soundtrack as "Tau-9".||On A Rail: Right after launching the Rocket.|
|"Hard Technology Rock"||A rock song mixed with a bit of techno sound.||The chapter "Forget About Freeman!".|
|"Steam In The Pipes"||Reused for the Half-Life 2 soundtrack as "Negative Pressure".||Lambda Core: Opening the portal to Xen.|
|"Electric Guitar Ambiance"||As the name says, an ambient track made primarily out of electric guitar sounds. Reused for the Half-Life 2 soundtrack as "Escape Array".||Surface Tension: During the area with Laser Tripmines and a Sniper.|
|"Dimensionless Deepness"||Reused for the Half-Life 2 soundtrack as "Dirac Shore".||Xen: The butterfly-activated teleporter room leading to Gonarch's lair.|
|"Military Precision"||A slow start, with a military-sounding remainder.||Residue Processing: After meeting up with a security guard (the same guard that is killed by a Barnacle, allowing the player to take his gun).|
|"Jungle Drums"||A tribal-sounding track, primarily drums.||The chapter Gonarch's Lair.|
|"Traveling Through Limbo"||Reused for the Half-Life 2 soundtrack as "Singularity".||Nihilanth: While fighting the Nihilanth.|
|"Credits / Closing Theme"||Remixed for the Half-Life 2 soundtrack as "Tracking Device".||During the credits.|
|"Threatening Short"||Reused for the Half-Life 2 soundtrack as "Xen Relay".||Xen: After entering Xen. Also at the diabolical portal leading to the Nihilanth.|
|"Dark Piano Short"|| Questionable Ethics: First seeing an Alien Grunt (trapped in a glass enclosure).|
Surface Tension: Core of the missile storage room.
|"Sharp Fear Short"||Power Up: Killing the Gargantua.|
- In several pre-release videos of Half-Life, different version of Diabolical Adrenaline Guitar can be heard. It was likely changed in Summer 1998, as the old version can be heard in E3 1998 Gruntfight video and is not heard in Half-Life: Day One.
- The track Dark Piano Short appears to be a small piece of the Quake 2 track Stealth Frag.
- The fan-made Freeman's Mind, a run-through of Half-Life with commentary about what Freeman is allegedly thinking as he goes through the game, features the opening of Military Precision for the title graphic.
- This is the only soundtrack from the Half-Life series that has been released in a high quality (music industry grade) format, the other CD releases from the series were sourced from low quality 128kbit/s MP3 masters.
- Vague Voices, Steam In The Pipes, Traveling Through Limbo, Dimensionless Deepness, and Threatening Short all have the name "prospero" in the game files. This is because these five songs were originally to be used in one of Valve's unused games, Prospero.