That's pretty cool. It's always nice to see how others work. What's the app you're using to create the sprites? Looks a bit like photoshop, but more streamlined?
I took someone elses advice in the early posts and used Aseprite, which I was ultimately happy with, but was lacking a few features that would have helped immensely, such as a copy/paste selection (if there was one, I probably missed it as it was my first time using it).