1- Create a game where you are a leader of a team that you collected and are not the same species as you, fights are in 1vs1 battles, and you order them to do things. It can be monsters or anything else that you choose.
2- Don't use any copyrighted material. There are many free assets out there for anything, or create your own.
3- Try to put an objective in the game.. A main goal that the player is trying to achieve.
4- It doesn't have to be a topdown 2D game, or even RPG. It can be anything that you want as long as it follows the basic structure.