5. Distant Worlds: Universe
The Distant Worlds: Universe is a package of the main game and several awesome expansions, all gathered into one game which is probably one of the best 4X games of all times for a bih majority of players out there. Published by Matrix Games/Slitherine, we can already tell that these guys mean business, as publishers of some of the most complicated and most wonderful, deep space strategies. With 1400 star systems and around 50.000 planets, you will definitely have a lot to explore, expand and exploit during your games! Engage in research, diplomacy, espionage, play as a law abiding factions or as a sapce pirate and conqueror, it is all up to you.
To some, the mere extent of this game may be frightening, and it is definitely nothing something for the weak of heart.
You can get Distant Worlds Universe on Steam.