In order for 2 players to play the game, they follow the same setup rules as the 4-player game. The 2 players sit opposite each other, and 2 more "virtual" players sit between them, one on each side.
These 2 virtual players do not choose a race, do not place a Main Reactor, do not receive any credits, and do not place a Player Marker on the Score Board. Also, since only 2 actual players are playing, only 2 Objective Cards are drawn.
At the beginning of every year, both players draw a hand of 6 cards. For each of the virtual players, also draw 6 cards (without looking at them) and place them on a pile where the player is supposed to be on the table.
Every turn, after a player selects his card, he "gives" the remaining cards to the virtual player next to him, placing them next to where his pile of cards is. He then takes that pile (the virtual player's current hand), looks at it and discards a card.
He then gives the remaining cards to his opponent. If done correctly, all the players (both actual and virtual) should have the same number of cards in front of them each turn. Keep in mind that any racial ability that allows a player to interact with the hands of the other players may be used on the virtual players' hands as well. The rest of the game plays as normal.
A slightly different set of 2-player rules was proposed by Kim Williams and since many people find it enjoyable, we include it here for those who want to try it. With these rules there is no need for the 2 virtual players.
Set up the Location deck as in a 4-player game. At the beginning of every year, deal 6 cards to each player. Before every turn (including the first one), each player draws an additional card from the deck.
Both players then choose one card from their hand to play, and one card to discard. They then pass the remaining cards to the other player.