Imperium Galactum

Not to be confused with the much, much later Imperium Galactica , this was
the first fully-functional commercial “4X” space game to hit the U.S. Many of
the most important features in later 4X games appeared in this one: ship
design, guerrilla warfare on captured planets, troop transports. It did not
feature tactical space battles, however.

The main game screen displayed a grid of dots, with star systems shown by a
larger circle with a color representing the star’s type. Stars could have
zero, one, or two inhabitable planets. Warships could be custom designed and
were tracked individually with a maximum of 255 war ships per player in
existence at one time. Transports could carry either colonists and troops and
traders carried metal or food surpluses to where they were needed. During an
invasion, the respective armies from each player would fight until one force
was destroyed. However, planets thus captured could suffer from guerrilla
resistance for several turns and if not eradicated could overthrow the
invaders or assist your opponent’s armies in the event of a counter invasion.

Given the tiny systems it ran on, this game did a very good job of simulating
many important considerations, and was the first introduction of some of the
things that have become staples in 4X space games; most notably ship design
and refits.