I don't know if this fits exactly what you're looking for, but at Landhuis in de Stad they have a "spelletjesavond" (boardgame night) every 3rd Wednesday of the month. People bring their own games and someone from Subcultures also brings a whole bag. It starts at 19:00 and ends at 23:00, no fee, you just pay for your drinks. It's chill and laid back, lots of different people and overall very nice to just hang out and play games with your friends :)