Sure, here's an example of a simple 3D game in which you walk on a walkway and collect coins to win prizes. The game can be played on a smartphone.
To play the game, simply copy the above code into an HTML file and open it in a web browser on your smartphone. The game will display a walkway with coins on it. By tapping on the coins, you collect them and increase your score. Once you collect 10 coins, the prize message "You win!" will appear. The walkway will continuously rotate to create a 3D effect.