Old Unity project, weird way of creating assets

Hello everyone,

First of all, i will admit that i am still learning unity, so please bear with me.

So i have been working with a 2d mobile project that was given to me for the last 2 months or so that was created with unity 3.4.2. It is an extremely old project.

I have successfully upgraded the project to unity 2019.1.0, and it runs greats. I now, however, wish to re-theme the project.

The problem I am running into is that I don't recognize how whoever created the project made their assets. For example, there are characters for the game imported with just a mat file. All of the character's individual animation frames will be included on this mat file, almost like a sprite sheet. I then apply this mat file to a prefab mesh renderer along with a mesh and shader. I usually see this done with just a sprite renderer.

Basically, im trying to discover enough information just to google the process and research on how to create new assets for this game. I realize that is may not be enough information for anyone trying to help me, but admittedly, it is rather difficult to write it up.

If anyone has some information that may be helpful, I would be super grateful.

 

If I can recall correctly most of the 2D features of Unity were not available in 3.x. 2D colliders did not exist for sure, and perhaps sprites didnt too. So I would convert those textures to sprites.