I say density, though Elite Dangerous puts a spin on how large the map should be.

In Elite Dangerous, most of the galaxy is unexplored. The Bubble (human inhabited area) is fully explored, which steadily dwindles as you go to about 1k ly outside the Bubble. Out there, you’re basically on your own.

When you explore and map unexplored areas, you actually get some money depending on the quality of your finds. If you find some Earth-like planets, for instance, you can get a lot of money from exploring. There is also an inexhaustible supply of systems to explore, so there’s no need to worry about running out.

Another game with interesting worldbuilding is White or Black (by ZeroCreation).

In that one, humanity nearly destroyed itself after an incredibly devastating WW3. Therefore, to avoid the constant Cycling of Empires, a band of philosophers and religious people tried to make one final civilization that lasts forever, which completed its rise to world domination in the late 21st century. Some interesting tidbits about this final civilization:

• The final civilization restricts learning and innovation to things it deems safe to consume. It considers certain works to have a destabilizing effect on people, so it only allows trusted individuals to use them to achieve the civilization’s goals.
• The human species in the far future now engages with symbiosis with another species. As far as I can tell, these future humans mainly photosynthesize.
• Emotion is considered to be an outright SCP. The final civilization allows some of it, but too much can make areas uninhabitable.

The Pegasus Expedition

The worldbuilding is mostly based around the Pegasus Galaxy and how humanity wants to exploit it. The premise is this: Humanity is getting torn apart by an aggressive alien race called the Colossals, so they sent three fleets to the Pegasus Galaxy to get some resources and reinforcements. These fleets consist of the Middle East, the US, and the EU (the EU is playable); the Chinese fleets are instead holding the line by Earth.

When humanity enters the Pegasus Galaxy, they get a very frosty reception. They appear in an organization’s territory who immediate try to push the humans back to their portal. The organization is instead wiped out by the humans, and the organization’s bosses - resembling the Roman Empire - tells humanity to back off or the Empire will kick them out.

There’s some politics stuff that happens in the Middle Eastern and US fleets later on, as well as a Flood/Thing-esque crisis that shows up. In the end, the EU gathers up all of its new friends in the Pegasus Galaxy to push through Flood/Thing turf and rescue the humans on Earth.

The gameplay is a bit dodgy but I think the worldbuilding and story are rock solid.