Yes, he's both the dev and the artist
As a gamedev myself, I can send you some tips; first of all come up with your idea before you start making the game. Brainstorm ideas for how you want it to look and how it will play, what characters are gonna be involved, how the camera angle works, etc. Once you have figured it out, start to write down exactly what you have came up with, how the game is supposed to look and play. I recommend the app Obsidian, it's completely free and open source and has a lot of resources.
Then once the game is done on paper, start by working with the art, do the concept art and then the basic sprites of the characters. Once you have the character sprites, you can make a very basic scenario just to test things out and you can work on the programming part. Make the game mechanics, how everything is supposed to play and then start to add the characters and scenario elements. This process goes back and forth, so keep on going until you are done with your plan that you have wrote down.