Can I Modify Game Resources?

Is it okay for me to modify the game resources, like the default sprites or the walking cycle?
I'm not asking how to do this, because I already know how, I'm just not sure if there are any legal problems or anything of that sort if I share modified files, even without making any profit off of it, and ONLY sharing it in this community.

KS is open source, and there have been mods/extended editions/stuff before, so you're basically very welcome to modify the game. as usual, decent credits should be given.

Oh, I had no idea, thank you very much for clearing that up.

There's a license bundled with the source code that tells you what you can and can't do with it.