anchor.diff:  , fetchFromGitHub
   , fetchpatch
   , fetchurl
  -, fetchzip
  +, bzip2
   , cmake
   , pkg-config
   , gettext
  +, libsodium
   , SDL2
  +, SDL_audiolib
   , SDL2_image
   , fmt
   , libpng
  
positive.code:     substituteInPlace Source/init.cpp --replace "/usr/share/diasurgical/devilutionx/" "${placeholder "out"}/share/diasurgical/devilutionx/"
  
      # download dependencies ahead of time
      substituteInPlace 3rdParty/asio/CMakeLists.txt --replace "https://github.com/diasurgical/asio/archive/ebeff99f539da23d27c2e8d4bdbc1ee011968644.tar.gz" "${asio}"
      substituteInPlace 3rdParty/SDL_audiolib/CMakeLists.txt --replace "https://github.com/realnc/SDL_audiolib/archive/aa79660eba4467a44f9dcaecf26b0f0a000abfd7.tar.gz" "${SDL_audiolib}"
      substituteInPlace 3rdParty/simpleini/CMakeLists.txt --replace "https://github.com/brofield/simpleini/archive/7bca74f6535a37846162383e52071f380c99a43a.zip" "${simpleini}"
    '';
  
    cmakeFlags = [
      "-DBINARY_RELEASE=ON"
      "-DVERSION_NUM=${version}"
      "-DPACKET_ENCRYPTION=OFF" # FIXME: build with libsodium
      "-DDISABLE_ZERO_TIER=ON" # FIXME: build with libzt
    ];
  
    nativeBuildInputs = [
  
negative.code: 
  let
    # TODO: submit a PR upstream to allow system copies of these libraries where possible
  
    # fork with patches, far behind upstream
    asio = fetchurl {
      url = "https://github.com/diasurgical/asio/archive/ebeff99f539da23d27c2e8d4bdbc1ee011968644.tar.gz";
      sha256 = "0vhb4cig40mm0a98i74grpmfkcmby8zxg6vqa38dpryxpgvp5fw8";
    };
  
    # fork with patches, upstream seems to be dead
    libmpq = fetchurl {
      url = "https://github.com/diasurgical/libmpq/archive/0f10bd1600f406b13932bf5351ba713361262184.tar.gz";
      sha256 = "sha256-7hc/Xtsg8WJIJljLydS7hLZA9lEEHWhsCteyrxK68qE=";
    };
  
    # not "real" package with pkg-config or cmake file, just collection of source files
    libsmackerdec = fetchurl {
      url = "https://github.com/diasurgical/libsmackerdec/archive/2997ee0e41e91bb723003bc09234be553b190e38.tar.gz";
      sha256 = "sha256-QMDcIZQ94i4VPVanmSxiGkKgxWx82DP4uE+Q5I2nU+o=";
    };
  
    # fork with patches, far behind upstream
    libzt = fetchFromGitHub {
      owner = "diasurgical";
      repo = "libzt";
      fetchSubmodules = true;
      rev = "a34ba7f1cc2e41b05badd25d1b01fdc5fd2f4e02";
      sha256 = "sha256-tyIPt+7OTi5W+5X/ixQP1puOKdhrqRZtpwXlWFBFpc8=";
    };
  
    # missing pkg-config and/or cmake file
    simpleini = fetchurl {
      url = "https://github.com/brofield/simpleini/archive/9b3ed7ec815997bc8c5b9edf140d6bde653e1458.tar.gz";
      sha256 = "sha256-93kuyp8/ew7okW/6ThJMtLMZsR1YSeFcXu9Y65ELBFE==";
    };
  in
  
  stdenv.mkDerivation rec {
    pname = "devilutionx";
    version = "1.4.0";
  
    src = fetchFromGitHub {
      owner = "diasurgical";
      repo = "devilutionX";
      rev = version;
      sha256 = "sha256-uuIPTdgGpHA8j1M8b+kfnBuiJ5mdS9rckvEfn2h7lmo=";
    };
  
    patches = [
      (fetchpatch {
        url = "https://github.com/diasurgical/devilutionX/commit/03b22352fc9e1ecb88b20a053c90c04a50717267.patch";
        sha256 = "sha256-5aAwi1NV8P+nLLbEEnlwLGNQCQBb0nQkIVe5tR5Shsw=";
      })
    ];
  
  