anchor.diff: -{ stdenv, fetchFromGitHub, cmake, pkgconfig, SDL2, SDL2_mixer, alsaLib, libpng, pcre }:
  +{ stdenv, fetchFromGitHub, cmake, pkgconfig, SDL2, SDL2_mixer, alsaLib, libpng
  +, pcre, graphicsmagick, makeDesktopItem }:
   
   stdenv.mkDerivation rec {
   
  
positive.code:     sha256 = "0mavmwikfsyr5sp65sl8dqknl1yz7c7ds53y1qkma24vsikz3k64";
    };
  
    nativeBuildInputs = [ cmake pkgconfig ];
  
    buildInputs = [ SDL2 SDL2_mixer alsaLib libpng pcre ];
  
  
negative.code: 
    # Help CMake find SDL_mixer.h
    NIX_CFLAGS_COMPILE = "-I${SDL2_mixer}/include/SDL2";
  
    # Create "ivan.desktop" file
    ivanDesktop = makeDesktopItem {
      name = pname;
      exec = pname;
      icon = "ivan.png";
      desktopName = "IVAN";
      genericName = pname;
      categories = "Game;AdventureGame;RolePlaying;";
      comment = meta.description;
    };
  
    # Create appropriate directories. Convert "Icon.bmp" to "ivan.png", then copy
    # it and "ivan.desktop" to these directories.
    postInstall = ''
      mkdir -p $out/share/applications
      mkdir -p $out/share/icons/hicolor/32x32/apps
      gm convert $src/Graphics/Icon.bmp $out/share/icons/hicolor/32x32/apps/ivan.png
      cp ${ivanDesktop}/share/applications/* $out/share/applications
    '';
  
    meta = with stdenv.lib; {
      description = "Graphical roguelike game";
  