One of the cooler ideas in 13th Age is the icons, thirteen powerful figures who have their fingers in intrigues all around the campaign. In fact, I consider the breadth of their influence their defining factor rather than their personal power.
I am starting a new project where I will facilitate the creation of a sandbox setting. The working title is “Not An Adventure Path”. I’ve always been leery of the expression “Adventure Path” because of the implied linear nature. I find linear campaigns to be limiting to PCs, and to be brittle, depending on specific results and outcomes. Instead, we will be developing a set of related adventures that can be resilient in the face of PC intervention (remember, plots exist for PCs to tamper with).
I realized recently that something like the icons could make a wonderful fit for a sandbox, especially when PCs already have relationships (positive, negative, or conflicted) to the icons. These provide built-in hooks for adventures by drawing up sides and knowing who the major figures are.