It's what hopefully everyone of us did with our siblings or play buddies when we were children. 
Play fighting and roughhousing as I approach them are essentially interactive movement games focusing on fighting. Unlike some martial arts or fighting sports, they are less serious. As the facilitator, I create sparring scenarios often similar to wrestling and sometimes leaned on a story-line that makes it almost theatre-like and helps to immerse yourself in the situation. 
Oftentimes, the task of a game is to touch a body part of your partner (e.g. the shoulder, knee etc. ) and avoid being touched there yourself. Other games are more story-line oriented, others are about defending yourself from being hugged behind the back, and in others you'll defend your favorite spot on the ground. The scalability and possibilities are endless!
The overarching intent here is to keep learning how to play well with others. This kind of play will also develop physical skills, but in the end, we practice engaging with others.
The games you'll play might seem competitive, but we aim not just to win but to help each other become better.

My classes are designed to be engaging and approachable for everyone, regardless of athletic ability. I always look to create a supportive atmosphere, provide safety, and make you struggle but succeed as well.