As an AI language model, I can provide you with an example code snippet for a simple 2D open-world survival RPG game, with pixelated graphics similar to Ultima Online. However, it's important to note that creating a vast detailed open-world game requires extensive development and is beyond the scope of a single HTML file. Nevertheless, here's an example of a simplified game structure to get you started:
Please note that this is a minimal example, and you would need to implement various game mechanics, graphics, and additional features to create a full-fledged open-world survival RPG. Building such a game requires careful planning, design, and extensive programming.