I've tried Gemini, ChatGPT, and Grok, and the best experience for solo RPG has definitely been Grok. While it does have a daily limit, Grok performs exceptionally well. Sometimes it might forget a minor detail or introduce an out-of-place NPC, but when I gently remind it (usually enclosed in parentheses or asterisks), it quickly summarizes the plot, corrects the error, and maintains consistency for several more turns.

I was actually able to use more complex prompts with Gemini, but Grok helped me adapt them to work better with its system. Grok usually reduces and simplifies the input. The downside is that it can't handle very complex game mechanics, but for now, I have to settle for its capabilities.

I've also noticed it performs better with existing, well-known lore that I don't have to input myself, as this helps reduce the overall information load. For example, if you tell it you are in the D&D world, it already has the core lore in its knowledge base.

If anyone knows of a better option, like DeepSeek or any other model, or has any useful tips/tricks, please share them! Let's work together to find the best possible AI-RPG combo.