This addon is for the game first pixel shooter as a Downloadable content with a zombie map and singleplayer map
1.after downloading the .rar open it till you get to a .txt files, put the .txt's on your desktop
2.open your f.p.s.exe from the f.p.s folder
3.then go to level editor click the letter 'o' then click load editable then while you are on the thing that wants you to get a file go on your desktop then open up the .txt
4.then play!