The suffix is likely the username or abbreviation of the creator. Searching for "jjzd developer" or "jjzd games" on platforms like itch.io or community-run wikis may lead you to the original project page where you can find the most recent or "complete" version of the game. 2. Community Forums Niche projects like this are often hosted and discussed on: F95zone: A common hub for indie simulation games.
Use a tool like VirusTotal to check the file before opening it. Breeding_City_v0.1_jjzd.rar
If you are looking for this file to download it, be cautious with .rar archives from unknown sources. The suffix is likely the username or abbreviation