What tools do you use to make these assets?
I made it with the Pico8 sprite editor. There is a Pico8 clone, that can do pretty much the same called Liko12. You can find it here: https://ramilego4game.itch.io/liko12
It's good to have some fun. Its limitations make you finish games and dont get into huge ambitious projects that you never complete. It includes everything you need to make a game ( sprite editor, code editor, sound and music editor and map editor). Most people use it to get into gamejams. Its like a toy, you have fun with it, but you also need free time to play with it.