I'm building a game with a similar idea. encounters are controlled by the AI. there is a classic RPG system built around it and human generated content for the world and story.
while it is true that there is a gap between what most LLMs "know" and current time that gap is getting smaller not larger with time, it is also possible to teach a model pass the knowledge cut-off with tools and an LLM might be encouraged to be aware of the gap and reach out for the latest information when it might have changed (pi is still pi but the country with the most people might have changed)
support for typescript as long as you are only using it for type checking, not if you are also using features that are not supported in the javascript version you are targeting.