It's a Doom source port playing environment that requires the original DOS executables. If you're thinking that's a dumb idea, forget about it and check out:

• GZDoom
• PrBoom+
• Chocolate Doom

This works on my machine (Windows 7 x64, Visual Studio 2015); send a pull-request if you figure out a better way to make this more useful for non-Windows users.

• DoomBox requires DOSBox (included in the repo).
  • DOSBox requires SDL 1.2 (SDL 2.0 is apparently not supported).
    • Download the source code for your platform from the SDL website.
    • Shove the contents of the .zip's include directory into the repo's SDL-1.2.15\include directory.
    • SDL 1.2's development libraries don't work with VS2015, so you'll need to compile it yourself.
      • Change the active solution configuration to "Release".
      • Copy the following files to the repo's visualc_net directory:
        • VisualC\SDLmain\Release\SDLmain.lib
        • VisualC\SDLmain\Release\SDLmain.pdb
        • VisualC\SDL\Release\SDL.dll
        • VisualC\SDL\Release\SDL.pdb
        • VisualC\Release\SDL.lib
    • SDL 1.2 requires libpng:
      • Download the .zip from the "Source code" section of the libpng website.
      • Extract the .zip to a temporary directory, such that the temporary folder contains the lpng1629 (or similar) folder.
      • Now download the .zip from the "Source code" section of the zlib website.
      • Extract the .zip to the same temporary directory, such that the temporary folder contains the zlib-1.2.11 (or similar) folder.
        • Open lpng1629\projects\vstudio\zlib.props in a text editor and change the value of ZLibSrcDir to this new folder.
      • Copy the .h files from the lpng1629 folder and the zlib-1.2.11 folder to the repo's include directory.
      • Open lpng1629\projects\vstudio\vstudio.sln in Visual Studio.
        • Change the active solution configuration to "Release Library".
        • On the toolbar at the top of the screen, click Build, then Configuration Manager....
        • Uncheck pngstest (not pngtest), pngunknown, and pngvalid.
        • Build the solution.
        • In the lpng1629\projects\vstudio\Release Library\ folder, copy zlib.lib and libpng16.lib to the repo's visualc_net directory. Rename libpng16.lib to libpng.lib.
  • DOSBox requires SDL_Net.
    • Download the Binary SDL_net-devel .zip for your platform from the SDL_Net webpage.
    • Shove the contents of the .zip's lib\x86 directory (assuming Windows x86) into the repo's visualc_net directory.
    • Shove the contents of the .zip's include directory into the repo's include directory.
  • DOSBox requires Curses (even though it won't actually be used with the default settings).
    • Download PDCurses here.
    • Copy the .h files from the .zip to the repo's include directory.
    • Copy the .lib and .dll files from the .zip to the repo's visualc_net directory, and rename them from pdcurses.* to curses.*.
  • Now DOSBox should compile and link correctly.