Rocksteady's Batman: Arkham City is, in our opinion, the greatest Batman game ever made. Unfortunately it released back in 2011 on PC, Xbox 360 and PS3, so it's not looking too amazing these days. Fortunately mod maker GPUnity has released an HD Texture Pack to make Arkham City look much more appealing. You can download it below, and we've got instructions on how to install it.
1. In-Game Graphics Settings
Here are the settings you'll need to activate or deactivate in the game's options to get the Texture Pack working, we suggest you change them first before installing. Don't worry, the pack activates its own version of these and you're only disabling them so they don't clash.
2. Find And Edit BmEngine.ini
3. Open Texmod and Activate Textures
The Texmod program comes in the texture zip file. Open it, select Package Mode, and find your BatmanAC.exe file which if you're using Steam will be in the Steamapps/Batman Arkham City GOTY folder. We placed the textures and Texmod into this folder so it was easier to keep track of it, but that's up to you.
Then go to the smaller folder icon and use it to find the downloaded texture files. Run the game with selected texture(s). Bear in mind that only one cape can be selected at this time.
It's great of GPUnity to make this pack available, especially as the consoles received an "improved" version of City and Asylum in the Batman: Return To Arkham collection. Fortunately that was kind of awful, so this pack will end up being much better. It's in early days yet, but GPUnity continues to work on it. He's also the creator of Texture Packs for both Arkham Asylum and Nier Automata, so he's pretty great.