Sure, I can create a simple random Amiga-style game as a single HTML file using JavaScript. Here's an example:
This game creates a canvas element and renders a player character (represented by a white rectangle) in the middle of the screen. The player can move the character using arrow keys to increase their score. The current score is displayed at the top left corner of the screen. The game uses an Amiga-style font to create a retro look. Please note that you would need to have the "AmigaFont" font file available in the same directory as the HTML file for it to display correctly.
Feel free to modify and enhance this code to add compelling game mechanics and more visual elements to make it a complete, finished game.