As an AI text-based model, I can provide you with an example of a simple game implemented as a single HTML file using JavaScript. However, please note that I cannot create or include any jump scares as per your warning.
Below is an example of a game where you need to navigate a character (represented by a pictogram) around obstacles on a smartphone:
In this example, the game involves moving a character (represented by a pictogram) up and down to avoid a red obstacle. The character can be controlled using the arrow keys on the keyboard, and if the character collides with the obstacle, a game over alert is displayed. The obstacle will reset once it goes off-screen. Remember to replace `'emozi_all/game.png'` with the actual path to your character pictogram image.
Please note that this is a simple example to illustrate the structure of a game implemented in a single HTML file using JavaScript. Feel free to modify and enhance it according to your requirements and desired gameplay.