There is a huge (almost endless) variety of species that can evolve via DNA chains, and the random tile map board setup is constantly changing due to certain random events (e.g., Erosion, Greenhouse and icehouse Earth, and Milankovich cycles), Catastrophes (e.g., an Impact event or a solar flare), and the addition of new Biome tiles during play.
American | American Civil War | American Broadcasting Company | American football | African American | American Idol | American Revolutionary War | American Revolution | American Association for the Advancement of Science | American Red Cross | American Library Association | American Museum of Natural History | American Express | American Academy of Arts and Sciences | American League | American Association | American Heart Association | American comic book | American Institute of Architects | American Airlines | American Hockey League | Spanish-American War | Pan American Games | American Cancer Society | Whitney Museum of American Art | American Ballet Theatre | American Legion | American University | Union (American Civil War) | Scientific American |