Sure, here's a simplified implementation of a battle royale game within a single HTML file using JavaScript:
Lobby
Gun Slot
Vault
Store
Diamonds
Gold Coins
Training Spot
New Map
This is a basic structure for a battle royale game where the game elements such as lobby, gun slot, vault, store, diamonds, gold coins, training spot, and new map are displayed on the screen. The `startGame` function is called when the page loads, which reveals these elements and can be expanded upon with further game processing logic. The styling can be customized to match your design requirements.