anchor.diff:  { stdenv, callPackage, fetchurl, makeWrapper
   # Begin libraries
  -, alsaLib, libX11, libXcursor, libXinerama, libXrandr, libXi
  +, alsaLib, libX11, libXcursor, libXinerama, libXrandr, libXi, mesa_noglu
   # Begin download parameters
   , username ? ""
   , password ? ""
   }:
   
   let
  -  version = "0.12.20";
  +  version = "0.12.28";
   
     fetch = callPackage ./fetch.nix { username = username; password = password; };
     arch = if stdenv.system == "x86_64-linux" then "x64"
  
positive.code:     libXinerama
      libXrandr
      libXi
    ];
  
    buildInputs = [ makeWrapper ];
  
negative.code:   variants = {
      x64 = {
        url = "https://www.factorio.com/get-download/${version}/alpha/linux64";
        sha256 = "01si5n9hb2h0c5q8k3hr3nphsakp9kki84qyp70dgddwqsn8wfjl";
      };
  
      x32 = {
        url = "https://www.factorio.com/get-download/${version}/alpha/linux32";
        sha256 = "13h013ixyhv4rpvh0jv5jry3mrwv65v57nqn16bjh3hr8ip70lkq";
      };
    };
  in
  