Sure, here's an example of a simple survival 3D game implemented as a single HTML file using JavaScript:
// Enclose the script within
This game sets up a canvas element and allows the player to control a red square using arrow keys. The goal is to survive as long as possible without hitting the boundaries of the canvas. The score increases over time. When the player hits a boundary, the game ends and the score is displayed. You can further enhance the game by adding 3D graphics, sound effects, and more gameplay mechanics.