Sure, here's an example of an HTML file that implements a simple FPS game with event triggers, in-game purchases, and a sidekick selection feature. The game consists of shooting zombies and assassins while performing different actions such as running, standing, eating, and daily life activities. Using scripts and coding
Please note that this example provides a basic structure for the game and does not include the actual implementation logic for each component. You would need to fill in the missing parts with specific game mechanics, visuals, and event handling based on your requirements.