There are several ways in which one can recognize a reputed rummy game development studio. The following are a few criteria to consider to recognize a suitable game studio:
Check the reviews and website to understand the background of the game development company.
Go through the portfolio of the company to check the previous works they have done, especially related to the rummy games.
Last but not least, check the qualifications and experience of the game developers who will work on the project and whether their expertise aligns with your requirements.