Sometimes OpenAI servers experience high traffic and block some requests. Try again at a later time.
The game has a lot of possibilities to explore, and it can be quite addictive. I know it well from personal experience.
Regarding the limit, if the story becomes too long (4000+ tokens), you may not be able to continue. I'm currently working on a partial solution for this issue.
Alternatively, it's possible that you've exceeded your OpenAI free trial quota. If that's the case, you'll need to create a new account (or pay).