Civilization V expansion Brave New World.
First, Firaxis picked three civilizations from underrepresented parts of the world: South America and Africa. Hence, Brazil, Zulu, and Morocco civilizations were added to the expansion.
Indonesia was also added because of the Civilization fan base there. "Even though you don't think of, say, Indonesia, as a big video game outlet and consumer market, the country is huge now," related lead designer Ed Beach. "More and more places like Indonesia and Brazil, you just can't ignore how important their growth is here in the 21st century."
Other civilizations were added because of their unique gameplay experience. For example, Portugal was chosen because it fit in well with the new trading system being added in the expansion.
"Portugal ... doesn't meet the geographic diversity requirement, because Europe was already heavily represented, but it's a fan favorite," noted developer Anton Strenger. "It's been requested for a long time, it's been in previous Civ expansions like Civ 4 and they were historically this awesome trading empire. Here we are adding this awesome trading system. That lends itself really easily to creating this cool trading-oriented civ. That was one of our earlier additions." Venice, too, lent itself to the trading system.
Meanwhile, Poland represented a Jack-of-All-Trades that could fit any gameplay strategy, and was also suited to the game's social policies.
Science and expansionism will be Assyria's strength, as Stenger pondered, "They kind of were the scientific powerhouse of the ancient era, especially since they sacked Babylon and stole all their scientific texts. What if they were this militaristic, expansionist science power? That's kind of how that started.".
The Shoshone were selected because the devs wanted a Native American civilization, and the Anasazi fascinated them. This civ is more of a defensive power, and Firaxis didn't want to make another variation on the aggressive Zulu, which is why the Sioux weren't picked. They also picked Pocatello over Sacajawea as the leader.
Civilization V: Brave New World will be released on the 9th July 2013.