If humanity was alone in its quest for knowledge about the universe (and figuring out how to best utilize the universe for maximum (insert cultural value here)) the game would feel lonely, it seems like a good idea to add other intelligent civilizations to the game, trading with another race is different from trading with your own because they might value different resources differently and value credits as nothing instead having alternate currencies (which are in turn, worthless to humans) what you do is buy the cheap stuff from your own system, sell it to the aliens who might have a higher price, and buy their cheaper stuff, and bring it back to your own system for maximum profit.