Having an evening to play once a month is a great idea!
It's all play, and I hope we never lose sight of that. I think what you mean is taking a break from our usual rigid and complex play, to play in a more free-form, simple play. To exchange our usually serious play, for a goofier version. Like serious tennis players playing badminton just for fun, without keeping score, or follwing the rules, just wacking the birdie.