Tips Don't mix patched with unpatched savefiles or the game could crash. I'm using Hex Workshop but here's a free one: www.softpedia.com/progDownload/tiny-hexer-Download-35737.html
Tutorial Open the game and create the number of gfwl-saves you have. Lets say you have 3 gfwl-savegames, create 3 new savegames (fill 3 slots with 0%). Now in savegame folder you should have save0.sgd, save1.sgd and save2.sgd. Backup C:\Program Files (x86)\Steam\userdata\\200260\remote Check below for other posible locations Your GFWL savegame have your GFWL username as prefix. -save#.sgd If the savegame is in another location outside steam: Steam\userdata\\\remote
Like in My Documents, your savegame not have your gfwl-username as prefix. But you need to patch it. Delete all files EXCLUDING these files: (remember the folder backup) profile.bin and -save#.sgd Open with a HEX editor the savefile you want -save#.sgd Lets say Sharkiller-save0.sgd Search Type HEX Image Arkham City: 00 00 00 03 00 Image Arkham Asylum: 00 00 01 The one after text, not the dots. [AA][AC] Select all the text BEFORE the searched text [AA][AC] And delete. Save and remove your gfwl usename prefix from the file. "save0.sgd" Check the patched savegame is in the correct path. (check below) Open the game and you have your working savegame there.
Final location of patched savegames Arkham City C:\Program Files (x86)\Steam\userdata\\200260\remote Arkham Asylum C:\Program Files (x86)\Steam\userdata\\35140\remote
Another posible locations for your savegames Arkham City C:\Program Files (x86)\Steam\userdata\\57400\remote C:\Program Files (x86)\Steam\userdata\\200260\remote %USERPROFILE%\Documents\WB Games\Batman Arkham City\SaveData %USERPROFILE%\Documents\WB Games\Batman Arkham City GOTY\SaveData