Imperium Galactica is a single-player game developed by Digital Reality and released in 1997. It has both the combat and resource management elements of a real-time strategy game and the vast research tree and colony-building aspects of traditional turn-based 'space-empire-building' 4X (eXpand, eXploit, eXplore, and eXterminate) games such as the Master of Orion series.
The player, in the role of Dante Johnson, begins the game with command of a small capital ship - a Guardian-class Destroyer - and three Raptor-class Fighters (later in the game the player would command up to 28 capital ships and 180 fighters in one fleet), and three colonies, named Achilles, Naxos and San Sterling, unable to move beyond the boundaries of the small sector assigned for him to defend and expand. The story, concerning the Galactic Empire's current status in the 4th millennium, during the 3200's, serves as an entry point, gradually introducing the player to new concepts (planet management, space battles, ground battles, research, component & ship production, diplomatic functions) as he rises through the ranks from Lieutenant to Captain, Commander, Admiral and eventually Grand Admiral (where all functions are unlocked and the player has full control), all the while revealing the character's shrouded past, revealing that Johnson is the Galactic Empire's secret weapon that was created in desperation, an android, through flashbacks.
Interestingly, regardless of the player's actions, the galaxy outside his or her view continues to take shape even as they are completing the "training" ranks prior to being promoted to Admiral. In this way, a player who quickly defeats his initial enemies at early ranks might enter the larger galaxy before the other races have been too badly hurt by the antagonist species, the Dargslan Kingdom. A player might also take an excessive amount of time in these "training" missions and get promoted to find that the entire galaxy has been conquered, making the situation almost hopeless except by exploiting game bugs.
Source: Wikipedia, "Imperium Galactica", available under the CC-BY-SA License.