Sure, here's an example of a simple 3D building RPG game implemented in a single HTML file using JavaScript and enclosed in `` tags. Please note that due to the limitations of the text-based format, the game's visual representation and interactivity may not be accurately portrayed.
<br><br>
<br>
<style>
#canvas {
width: 100%;
height: 100vh;
}
</style>
<canvas id="canvas"></canvas>
In this game, you'll see a canvas representing the game window. A player character (a green square) is displayed on the screen, and a building (a gray rectangle) is present. When you click on the building, an alert message will pop up indicating that you entered the building.
This is just a basic example to demonstrate the concept of a 3D building RPG game using JavaScript and HTML. You can further expand on this example by adding more features and functionality to make it a complete game experience.