Sure, I can help you create a roleplay game for 20 players using JavaScript within a single HTML file. Here's a basic example to get you started:
In this basic example, I've defined a `Player` class and a `Game` class. Each player has a name and can have additional properties and methods based on your game logic. The `Game` class contains properties for the players and any other required game details.
The `startGame` function initializes the game by creating 20 players and adding them to the game. You can then perform any further game actions or tasks and display the finished game state or outcome as required.
Please note that this is just the skeleton of a game and you would need to expand upon it by adding more game logic, interactivity, and visuals using pictograms or any other appropriate means.
Feel free to customize and modify the code according to your specific game requirements.