Sure! Below is a sample code for a simple realistic day shooter game implemented as a single HTML file using JavaScript. Please note that this is just a basic example and you can add more features and improve the game as per your requirements. The game can be played on a smartphone as well.
To play the game, save the above code into an HTML file (e.g., `realistic_day_shooter.html`) and open it in a web browser. The game will start automatically, and you can click/tap on the red target to shoot and increase your score.