Source SDK Base 2013

SDK Base Info & SDK 2006, 2007 (Legacy)

SDK Base 2013 (About)

Setup - SDK Base 2013 SP

Setup - SDK Base 2013 MP (TF2)

SDK Base Beta

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Source SDK Base 2013 - Singleplayer and Source SDK Base 2013 - Multiplayer are tools available to all Steam users which, as the name implies, is locked to Source 2013 engine branch, to prevent incompatible engine updates from making your mod unusable. Since Source 2013 was split into three sub-branches (originally two), there are Source SDK Base 2013 - Singleplayer (for singleplayer mods) and Source SDK Base 2013 - Multiplayer (for multiplayer mods).

Tip:Despite the names, both Source SDK Base 2013 - Singleplayer and Source SDK Base 2013 - Multiplayer ( only) can be used for singleplayer.
The Multiplayer branch provides additional features (static prop lightmaps, BSP compression, more ambient cubes per visleaf, and slightly newer code), which may be desirable over the Singleplayer branch if not using a base mod such as Mapbase and not making a single-player mod that does not modify game code.
The TF2 branch version of Source SDK Base 2013 - Multiplayer makes some changes which break singleplayer mode, such as save loading not working correctly[1] and attempting to load any map with maxplayers (singleplayer) and cl_localnetworkbackdoor both set to 1 will also crash the game[2] (not affected on "sourcetest" (Source Engine Test).

SDK Base versions

There are two versions of Source SDK Base(s) 2013:

• Source SDK Base 2013 - Multiplayer (AppID: 243750 - Click to Install)

Note:This branch originally runs on Source 2013 Multiplayer, but it has been upgraded to the Team Fortress 2 branch, which might be incompatible with mods built on legacy version of Source SDK Base 2013 - Multiplayer (that runs on Source 2013 Multiplayer).
To downgrade to legacy version of Source SDK Base 2013 Multiplayer, follow the instructions:

1. Open Steam, go to Source SDK 2013 Multiplayer, right click Properties
2. A window will open. Go to "Betas", select previous2021 beta branch.
3. Steam will automatically re-download the files. Once it's done, run Source SDK Base 2013 MP as normal, or use its tools.

• Source SDK Base 2013 - Singleplayer (AppID: 243730 - Click to Install)

Note:By default, many sourcemods (including Mapbase), will crash when launched, unless you select the upcoming branch.
To select upcoming branch, follow the instructions:

1. Open Steam, go to Source SDK 2013 Singleplayer, right click Properties
2. A window will open. Go to "Betas", select upcoming beta branch.
3. Steam will automatically re-download the files. Once it's done, try to launch the mod again.

Note:Currently, as of March 4, 2025, this branch hasn't been updated yet to received new features from Half-Life 2's 20th Anniversary Update (radial fog, classic particles, etc.) or the Team Fortress 2 branch.

Setting up & compiling code

To set up Source SDK 2013 and compiling mods, see:

• Setting up Source SDK Base 2013 Multiplayer - for Team Fortress 2 branch (using post-2025 Source SDK Base 2013 - Multiplayer)
• Setting up Source SDK Base 2013 Singleplayer - for Source 2013 Singleplayer (using Source SDK Base 2013 - Singleplayer)
  • Source code for this SDK is not yet updated, unlike TF2 branch, and will require using older version of Visual Studio or GCC to compile.
  • Also applies to legacy (pre-2025) version of Source SDK Base 2013 - Multiplayer.

SDK Base Content

Singleplayer branch

• Source Engine Test (sourcetest)
• Half-Life 2: Episode Two shared (ep2)
• Half-Life 2: Episode One shared (episodic)
• Half-Life 2 shared (hl2)
• Source 2013 Singleplayer branch (32-bit binaries only)

Multiplayer branch

• Source Engine Test (sourcetest)
  • Note:Source Engine Test can be only launched with 32-bit binaries only.
• Half-Life 2: Deathmatch shared (hl2mp)
• Half-Life 2 Complete (hl2_complete)
• Half-Life 2 shared (hl2)
• Team Fortress 2 branch (32/64-bit binaries)