Do you know how to open the developer console for your browser? Then you might be able to see and copy some kind of error message at the time a game ends.
If you don't know what the developer console is, if you tell me your operating system and the browser you use, I'll be able to find the key combination.
If you don't know what the developer console is, if you tell me your operating system and the browser you use, I'll be able to find the key combination.