The second book in the GURPS Traveller Alien Races series, Alien Races 2: Aslan and K'kree addresses the biology, home worlds, culture, and society of the fierce Aslan, the centaurian K'kree, and two minor species. It details their historical involvement with the Imperium, from first contact to present, and presents racial templates, rules for playing alien characters, and examples of unique technologies and ship designs.