Sure, here's an example of an idle game implemented as a single HTML file using JavaScript. This game assumes smartphone operation and incorporates pictograms.
Idle Clicker Game
Score: 0
This HTML file sets up a simple idle clicker game. The player can tap (click) on the click area and the score will increase. Additionally, the score also increases automatically over time, simulating idle progression. The score is displayed both numerically and using pictograms. You can replace the pictograms with any symbols or images you prefer.