Do you have a contract with said company? What are those terms? Can you prove you made it 100%? The code and graphics? A copyright case is long and expensive so

Do you have a contract with said company? What are those terms? Can you prove you made it 100%? The code and graphics? A copyright case is long and expensive so it may not be worth it to chase bad or no money. Pro bono maybe, but I doubt that too. I hope you learned a valuable lesson tho.