# A Survey of the Real-Time Metaverse: Challenges and Opportunities +
## 6 Metaverse Engine
### Artificial Intelligence (AI) and Machine Learning (ML)  
Artificial intelligence (AI) content generation plays a pivotal role in developing and enhancing the metaverse, a virtual universe where users can interact with each other and in digital environments in real-time [24]. Using AI to make content in a metaverse includes a lot of different technologies, such as procedural generation, natural language processing (NLP) [187], and large language models (LLMs) [188]. These technologies collectively create more immersive, interactive, and personalized user experiences. Procedural generation is a method in which content is created algorithmically rather than manually, allowing for the creation of vast and diverse virtual worlds within the metaverse. The procedural technique can generate everything from complex landscapes to intricate architecture and even entire ecosystems. Procedural generation ensures that the metaverse remains dynamic and expansive, offering users new and unique experiences each time they log in. The ability to automatically generate content also significantly reduces the time and resources needed for manual creation, enabling developers to focus on other aspects of the metaverse.  
NLP is another critical component in the AI content generation for the metaverse [187]. NLP enables more natural and intuitive interactions between users and virtual entities, including non-player characters (NPCs) and digital assistants [24]. By understanding and processing human language, NLP allows these virtual entities to respond appropriately to user inputs, facilitating more engaging and meaningful conversations. The NLP capability fosters a seamless and immersive user experience [189], as it bridges the gap between human communication and digital interaction. LLMs, such as GPT-4, further enhance the capabilities of NLP in the metaverse [188].  
These models are trained on vast datasets and can generate human-like text based on contextual understanding. LLMs can create complex narratives, generate dialogue for NPCs, and even assist in real-time translation between users of different languages. The integration of LLMs into the metaverse ensures that the virtual world is rich in content and can adapt to the diverse linguistic needs of its global user base. The combination of procedural generation, NLP, and LLMs in the metaverse leads to a highly dynamic and personalized user experience. For instance, users can explore unique environments tailored to their preferences, engage in meaningful conversations with virtual entities, and enjoy evolving narratives based on their interactions [190]. The advanced level of personalization not only enhances user engagement but also fosters a sense of connection and immersion within the virtual world. The AI-driven content generation ensures that the metaverse remains a vibrant and evolving space, continuously offering new experiences. In virtual environments such as the metaverse, AI-driven avatars and non-player characters (NPCs) serve distinct roles, each with unique functionalities and purposes. Although they both use artificial intelligence to power them, their approaches to user interaction, levels of autonomy, and overall goals in virtual spaces are fundamentally different.