Requires Texmod and New Millennium DLC.
You need to go in Batman Arkham Origins/Singleplayer/BMGame/Config then open BmEngine and search this line " AllowD3D11=True " and replace the True by False then save
go to C:Steam/SteamApps/common/Batman Arkham Origins/SinglePlayer/Binaries/Win32 and rename BatmanOrigins.exe to BatmanOriginsOriginal or something then rename texmod.exe to BatmanOrigins then simply run the game from steam, click the folder button in the top, select BatmanOriginsOriginal.exe then select the costume mods of your choice, then click run.
You need to go in Batman Arkham Origins/Singleplayer/BMGame/Config then open BmEngine and search this line " AllowD3D11=True " and replace the True by False then save
go to C:Steam/SteamApps/common/Batman Arkham Origins/SinglePlayer/Binaries/Win32 and rename BatmanOrigins.exe to BatmanOriginsOriginal or something then rename texmod.exe to BatmanOrigins then simply run the game from steam, click the folder button in the top, select BatmanOriginsOriginal.exe then select the costume mods of your choice, then click run.