that habitat building in the first game was a formulaic process that was improved upon in the sequel. The game's terrain deformation and Biome Brush were implemented to give the player control over their habitats by making them unique and individual, while making them simple enough to not alienate players that weren't as interested in the details of building an exhibit. The development team noted the change in conservation messages portrayed by zoos after the release of Zoo Tycoon, and worked to make Zoo Tycoon 2 feel up to date with current information and messaging. Expansion packs were built onto the original game up to four years after its initial release, with designer Linda Currie citing the team working on three expansions simultaneously during development. Updated mechanics in each expansion required changes to be made to all animals, to ensure that each expansion pack would not break the game. The team worked to make changes without altering the core systems in place, in order to make updates and QA testing easier, and with lower risk. Marketing Publisher Microsoft Game Studios ran several promotions involving the game, including a competition allowing kids to "Become a Zoo Keeper for the day" in the UK, and a competition to find "America's Favorite Zoo" in the US, an online vote which would result in a $25,000 grant from Microsoft to be put towards upkeep and maintenance. The contest consisted of three rounds, with the first round consisting of zoos being picked by a team of judges based on submitted press materials, which resulted in 15 semifinalists. Rounds two and three were done by fans in an online vote. In November 2004, Tulsa Zoo was declared the winner of the polls, and was awarded the grant. Expansion packs Endangered Species On October 18, 2005, Microsoft released the Zoo Tycoon 2: Endangered Species expansion pack. This expansion pack adds more rare animals, including the koala, gray wolf, Komodo dragon, scimitar-horned oryx, American bison and orangutan, as well as a number of new forms of transportation, including sky trams, jeep tours and elevated paths. The expansion also has a feature called "variant skins", which means that when the player adopts an animal, it may look different from normal members of its species (such as a White tiger and King Cheetah). African Adventure Zoo Tycoon 2: African Adventure, released in May 16, 2006, adds various new African animals