Recently, my 5-year-old daughter started playing Minecraft Pocket Edition. Right after I downloaded the game, she picked up the iPad, generated a new world, and began building a house. Minecraft has a bare-bones interface, with no helper tips or tutorial. How was she able to play so fluently on her first try?
Simple: she'd be watching her big brother play Minecraft on the family computer for months. She was ready.
Games have an experience arc of learning --> practicing --> mastering that's particularly well suited to group bonding. Everyone has to learn the rules, so there's a natural teach/learn social relationship between experienced players and newbies (e.g. my son and daughter). Good games are designed to let you "practice the rules" - you jump in, make mistakes and learn from them. Part of Minecraft's magic is that your mistakes are visible and easy to recover from. When Lila started building her first Minecraft house, she was wasn't sure of what to do - but she quickly figured it out by placing and hacking blocks.
Social engagement is the glue to holds people together over time. The beating heart of social engagement is shared activities -- things that you do together. Families who play Minecraft (like mine) are enjoying a digital version of what families have always done - playing games together to have fun and strengthen their bonds.
Because Minecraft is so easy to experiment with AND is missing the usual built-in tips and tutorials, players are learning the ropes from each other - and from the myriad Minecraft Wikis, fan pages and youtube videos that have proliferated to fill in the knowledge gaps. Sometimes, less is more when it comes to social engagement and UI.
If you want to create a digital service that drives SUSTAINED engagement, think about the shared activities that bring your players (AKA users, customers) together. What can people DO together (both synchronous and asynchronous)? How can they learn from each other? What can they co-create? How can they add value to each other's experience, even (or especially) when they're at different levels of mastery? These questions apply to ANY digital service that wants to build lasting social engagement. People will come for the service - but they'll stay for the relationships, and the activities that keep those relationships humming along.