Sure! Here's an example of a simple 3D roleplay game called "Opland" implemented as a single HTML file using JavaScript:
Opland - 3D Roleplay Game
This example sets up a simple game canvas with a player represented by a colored square. The player's position is controlled by touch events on a smartphone. The game loop continuously redraws the canvas and allows for game logic updates.
Please note that this example is a basic starting point for a game and can be expanded further to include more features, graphics, and gameplay mechanics based on your requirements.