Sublight Empire

Einstein's theory of relativity states that nothing is faster than light. This also applies to this game.
Information is radio signals propagating at the speed of light. These radio signals transmit your commands and the events you receive.
Spaceships move at a fraction of the speed of light. So it takes years for a command or a spaceship to reach its destination. When a battle takes place, you won't know about it until years later.
Apart from this, it is a classic 4X game.
In the beginning you rule a single star system and you are exploring and colonizing the surrounding systems.
Later on you will meet your opponents and you will have to defend and conquer colonies.
To win the game, you must conquer 2/3 of all stars.