Called "MOO" by the fans of this excellent game, Master of Orion and its sequel Master of Orion 2: Battle of Antares are widely considered two of the best space empire building games ever made. Not until Imperium Galactica II came out a month or so ago has there been a space game as good as the MOO series.

What makes these two games so incredibly addictive is their scope and flexibility. Call it Civilization in space, if you will. You can research technology and design your own ships. There is space combat and ground combat. You can take over a planet or destroy it to prevent the enemy from using it again. Diplomacy was a big part of the game.

Both games were made by Microprose. What they lacked in graphics and eyecandy they made up in gameplay. Despite its age, both are highly recommended.