This is a pretty big undertaking. No, there aren't mod tools. However, the game is made in Unity and all of the files are there for you to edit. There are programs out there that will let you unpack and repack assets files and see all the real stuff that makes up Broforce. You'll need to get Unity and learn UnityScript or C# or whichever language is used in the script files and you'll need to get familiar with an image manipulation program to edit characters and enemies iff you can actually find the files they're store in within the game files. There are more files than I can count inside of this game

Yes!!! please create opportunity to add user sprites and textures. and new Bros!
i like modding