And don't get rebellion unless graphics and some superships are super important to you, Diplomacy is probably the best bet if you want lots of mods.
Your points:
-Real time or in rounds: Real Time
-Research: Complex research tree, divided into Military, Civilian, and Defense.
-Diplomacy: Send envoys to other systems, do missions for other factions.
-Colonize planets: Yup.
--Multiplayer capability: Simple to use.
-Create your own ship models: You can.
-Create your own race: You can.
-Modifiable: Very modifiable.
Power does not corrupt. Fear corrupts... perhaps the fear of a loss of power.
