Source files for gm_fork, developed by Wouter Pleizier (aka Blueberry_pie)
Source release version 2016-04-30 (VMF version: 2016-04-30)

Download: https://www.dropbox.com/s/cd2qw4ros33ihx1/gm_fork_source.zip?dl=1
Mirror: https://drive.google.com/file/d/1UT58-vadCkYMSkYq_Be8l8i9rVGFn2K9/view

Feel free to use any of the content provided in this source release for any purpose you like. This includes modifying the map and distributing it, using parts of the map in your own maps and/or porting the map to other games. Please include a link to the original Workshop release if you do so, though.

I've put together some notes that may be useful. Please make sure you've read them before getting started with the source files.

The materials and models folders contain the custom content used in the map, so you'll need to place those in the directory of the game you're mapping for. Make sure that your version of Hammer has HL2, Ep1 and Ep2 mounted, as a fair amount of content from those games is used. (Alternatively, use GMad to extract the required content from the Workshop .gma file.)

The model sources (created in 3ds Max 2009) and their respective QC files are also included, in the modelsrc folder.

In addition to fork.vmf, there are some VMFs containing small sections of the map. These have been instanced and collapsed into the main map, but I figured it couldn't hurt to also include them separately.

Due to the large size and open nature of the map (as well as the lack of planning during development), visibility optimization happens almost exclusively through fade distances for props (and for some brush geometry using func_lods). I personally would not recommend this approach for other maps unless absolutely necessary, as Source simply isn't designed for it.

Compiling the map takes quite a while. VBSP and VVIS are pretty fast (thanks to the func_viscluster entities), but the HDR and LDR lighting take around 40 minutes each on my i5 2500K (overclocked to 4.2 GHz). I used Hammer's expert compile mode with the following settings:

VBSP: -nodefaultcubemap -allowdynamicpropsasstatic
VVIS: default settings
VRAD: -hdr -lights fork.rad -StaticPropLighting -StaticPropPolys -TextureShadows
VRAD: -ldr -lights fork.rad -StaticPropLighting -StaticPropPolys -TextureShadows

Make sure you use a custom VBSP with support for the func_detail_blocker entity and the -nodefaultcubemap and -allowdynamicpropsasstatic options. Any of the following compilers should work (I used the first one, but the others have more features/fixes).
Blueberry_pie's VBSP: https://www.dropbox.com/s/6qivlp37dh5c1po/vbsp-modified-20160429.zip?dl=1
THE_HAVOK's compilers: https://github.com/THE-HAVOK/source-sdk-2013/releases
Slartibarty's compilers (Slammin' Tools): https://drive.google.com/drive/folders/1hswQFn_BhwcLd91uBHnGKBPlCtuqPcX5

See this thread for more information on each of these compilers.[knockout.chat]

Refer to my displacement roads tutorial[knockout.chat] to see how the roads were made in this map. (Mirror: https://imgur.com/a/FDFNk)

The map has a single env_cubemap in a pitch black box, which effectively prevents all objects from reflecting anything. I felt that getting all the reflections right was too troublesome for a map like this, since a lot of env_cubemaps would be required (each of which would also increase the number of texture lookups for the CPU/GPU).

The water in the map uses a separate cubemap texture, which is defined in its material.

Due to the size of the map, generating the navmesh takes a long time (about 4 hours on my PC, if I remember correctly). If you want to generate your own, remember to set nav_quicksave to 1 or it will probably take over a week to process. I also recommend entering "ent_fire func_physbox kill" into the console beforehand, which removes the physics-based gates in a number of areas.

The nodegraph was created in GMod using the Nodegraph Editor addon. For that reason, no info_node entities are actually stored in the VMF.

The map uses some custom soundscapes, which can be found in the misc folder. When creating an addon, GMad disallows the packing of .txt files. This means that both soundscape files have to embedded into the BSP using bspzip or a similar tool.