From the rules:
Fight the Boss is a short, simple RPG. Why would you play it? Let's say you're getting together with your gaming group but not everyone has arrived yet. You can play this while waiting. Or anytime you want a quick, little adventure.
At the end of each game you always have to fight The Boss to complete the adventure. The Boss doesn't start off that strong in the beginning of the game, but as you get special favors from the [ Boss Master ], The Boss grows in power.