Sure, here's a simple game called "Pig Training" implemented as a single HTML file:
Pig Training Game
Score: 0
This game allows you to feed or train a pig using two buttons. Feeding the pig decreases its hunger level and increases its obedience level. Training the pig increases both hunger and obedience levels. The pig's hunger level increases over time, and if it reaches 10, the game is over. The score is displayed, indicating the pig's obedience level.