Obviously things like performance/stability and finishing progression
Content:
Using a similar design to the "ore caves", create spawning explorable locations for players to partake in. The following for examples.
- Dungeons
- Creature Lair/Caves - rare creature spawns that take a group to kill and drop special loot/resources
- Shipwreck - Spawns over water tiles, once entered a timer starts till the ship "sinks". Players have until then to loot the place and get out alive
- Underwater dungeons/lairs - Spawns over water tiles. Entry looks like a small whirl pool. Works similar to dungeons.
Wonders - Not sure if they're in the game yet, but i think this will be super valuable to reward exploration. These natural wonders that give special resources
The above things will significantly help reward players for exploring and create some dynamic interest while roaming the world.