I would like to see functional nebulas, meaning:

Instead of simply being a background image, they would be part of the game. There could be really neat visual effects too such as lightning flashes.

But the real functionality would involve penalties and technologies. For example:

- any ships in the nebula could suffer speed and sensor penalties if they don't have appropriate technology
- pirate ships could hide within nebulas and wait to attack
- outgunned ships could possibly have nebula tech that the chasers currently don't and safely hide within the confines of nebulas
- ships could also suffer a degree of damage per turn without reinforced hulls
- planets within nebulas would be very valuable assets given the hiding/protective functionality of the nebulas

There could be so much added to tactics that I think it would make a great addition to the game even if only by option.