Dxtory
You can play as Nightwing, Batgirl, Robin, or Red Hood in a 2-player online co-op or solo mode.
If you're interested in the PC version's modding capabilities, this video demonstrates how to use mods to play as Batman, despite him not being a standard playable character: Gotham Knights Build.26102022.part10.rar
Since you are likely looking at the PC version, you can enhance your experience with community-created mods, such as the Red Hood Mod or even a mod to play as Batman. You can play as Nightwing, Batgirl, Robin, or