Reach for the Stars is a science fiction strategy video game. It is the earliest known commercially published example of the 4X games (Explore, Expand, Exploit, Exterminate) genre. The player commands a home star in the galaxy, and then expands to form an interstellar empire by colonizing far-off worlds, building powerful starships, and researching new technologies.
Source: Wikipedia, "Reach for the Stars (computer game)," available under the CC-BY-SA License.
This game was simple, early multiplayer game (hot seat) where the players could starting from a single star, colonize a configurable star cluster.