Half-Life 2: Episode One
Half-Life 2: Episode One is the first in a series of games that reveal the aftermath of Half-Life 2 and launch a journey beyond City 17. It focuses on developing Alyx as a character.
Consciousness returns. Gordon and Alyx discover they've somehow escaped both the reactor explosion and the G-Man's malevolent grasp. Before they can ponder their miraculous survival, the crippled Citadel lurches back to life just long enough to initiate a self-destruct sequence. With Alyx at his side, Gordon must flee a city in chaos before the Citadel's final detonation turns City 17 into a toxic, mutant-infested crater.
Aside from the story, the game initially runs on Source 2006, which introduced new features such as HDR, Phong shading, and much more. The game was later upgraded to Source 2009, then again with Source 2013 Singleplayer.
Content
- Half-Life 2: Episode One (
episodic
) - Half-Life 2 maps (
hl2
) - Source shared (
hl2
) - Source 2013 Singleplayer engine branch
Chapters
Toggle chapters ![]() |
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![]() Undue Alarm ep1_citadel_00 |
![]() Direct Intervention ep1_citadel_03 |
![]() Lowlife ep1_c17_00 |
![]() Urban Flight ep1_c17_01 |
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![]() Exit 17 ep1_c17_05 |
Gallery
System Requirements
Windows (Old Engine/original requirement):
- OS: Windows 98 / ME, 2000, XP or later
- CPU: 1.2 GHz (Pentium 4 or Athlon 2800+ processor)
- RAM: 256 MB
- Disk space: 4.5 GB
- Direct3D 9.0 compatible video card (with atleast DirectX 7.0 compatibility level or higher)
Some features such as HDR requires DirectX 9.0 or higher graphics card
Windows (New Engine):
- OS: Windows 7 or later
- CPU: 1.7 GHz and/or Dual-core
- RAM: 1 GB
- Disk space: 6.5 GB (15GB+ recommended)
- Direct3D 9.0 compatible video card (with atleast DirectX 8.1 compatibility level or higher)

User using these OS can downgrade to previous version of the game by using the previous beta branch. But please note that this older branch does not include all the bug fixes that were introduced with Steam Deck update.
OS X:
- OS: OS X 10.5.8, 10.6.3 (up to 10.14.6)
- CPU: 2.0 GHz and/or Dual-core
- RAM: 1 GB
- Storage: 6.5 GB (15GB+ recommended)
- GPU: NVIDIA GeForce 8xxx series, ATI Radeon X1600, Intel HD Graphics 3000
OpenGL 2.1 compatible - Audio: OpenAL compatible
- Other: HDR is required to be enabled (see above)

User can manually build Intel 64-bit/Apple Silicon version of HL2 by following this guide.
Linux:
- OS: Ubuntu 12.04, SteamOS 1.0 or later
Other Linux distros supported. - CPU: 2.0 GHz and/or Dual-core
- RAM: 1 GB
- Storage: 6.5 GB (15GB+ recommended)
- GPU: NVIDIA GeForce 8xxx series, ATI Radeon X1600, Intel HD Graphics 3000
OpenGL 2.1 compatible - Audio: OpenAL compatible
- Other: HDR is required to be enabled (see above)


Limitations/Bugs
- For the list of Half-Life 2: Episode One bugs, see this GitHub page.
External links
Half-Life 2: Episode One on Combine OverWiki
Half-Life 2: Episode One on Wikipedia
GoldSrc
Half-Life (also on
PS2) •
Half-Life: Further Data •
Half-Life: Uplink •
Half-Life: Opposing Force •
Half-Life: Blue Shift •
Half-Life: Decay (only in
PS2) •
Deathmatch Classic
Source
Source 2
Related