Gameful is a community dedicated to the pursuit of making games that are of benefit. As part of this they run regular game design challenges. Here's my go at a game that encourages strangers in a public space to get to know each other:
A cafe: Friends sit drinking, chatting and having a bite to eat. It’s a common enough seen. But then the countdown begins. Folk eagerly finish off their drinks, revealing three digit numbers in the bottoms of their cups. None of these cups are the same; each has a unique number and a barcode on the underside of it, which was scanned when the cup was filled, so the system knows which numbers are in circulation. As the countdown continues, everyone looks to a large display, to see what the six digit number will be. Six digits? The six digit number is a compound of two of the three digit numbers that everyone has in their cup. When the number is announced it’s up to the holders of each half of the number to find one another, and claim their prize, free cake and cup of whatever they’re drinking to share while they get acquainted.
The whole set up could be used for paring people in any event where mixing up the social group is of benefit, such conferences, singles nights, fundraisers and, of course, networking events. In commercial settings it also has the benefit of encouraging people to finish their drinks, probably before they really want to, so they’ll order another one.