Just an FYI to anyone wondering the same as me: the viper and rat don't have a forward/backward sprite.
Windows failed to unzip this for me, so I had to download the .rar file and download 7zip to extract everything successfully.
Viewing post in Epic RPG World Pack - Sewers comments
Hello buddy! Thank you for your support. The tiny rat is just for the environment and It's designed to make them run around, near the wall's corners/edges. The mutant rat and viper follow the same standard as all other assets of this series (3/4 pose). Beholder is an exception and have more directions because it's a boss.
About the file, I tried here and It worked fine for me. I'll upload the zip file again just in case.