Creating Hooks Within a Sandbox

I'm currently working on a new mini-sandbox/point-crawl called Night Land, which I'll write more about in the coming weeks. It will run at around 60 pages, contain ten locations, half of those being adventure sites with maps and keyed areas. It's essentially a weird world to be explored, with no overriding objective or goal for PCs at the outset. 

This has presented challenges in determining engaging hooks I can plant in the setting, which encourages players to interact with adventure sites. The questions are what kinds of hooks to have and where/when to find them. In similar settings I've studied, it's often achieved with rumor tables, which I wanted to move away from.

Here is a list of additional ways to create hooks. These are broad conceptual ideas, which you could expand upon with specific narrative threads or plot-lines relevant to the setting:

• Active: an event that happens directly to PCs.
• Passive: events that happen and draw the PCs in.
• A social hub the party meets. 
• Developing major NPCs, stakeholders with motivations.
• A default action that offers hooks.
• Items (such as books, scrolls) about a place someone has been.
• Items the PCs already have.
• Items the PCs have encountered.
• NPCs informing players of what is going on.
• A current need of the PCs, such as a depleted resource.
• An encounter that needs to be resolved.
• Putting PCs in the path of an obstacle.
• Consequences of walking away from opportunities.
• Living world, events unfolding even if PCs weren't there.
• Situations that act as triggers. 
• Synergy between the different elements of the setting, one outcome triggering another.
• Timeline of events that occur unless the PCs preempt and stop them.