Short, compelling activities are the atomic units of any good core loop. Minecraft has building, mining and exploring block-worlds Duolingo and Lumosity have mini-games that level-up in difficulty Clash of Clans has resource gathering, training, and deploying troops. Facebook, Twitter and Instagram deliver an ever-changing variable-rewards stream of updates Without something engaging to DO, all the scaffolding and rewards in the world won’t keep people coming back for the long term. […]