Voi

Voi is a current-day market city in Kenya, Africa, and is a very important area for three levels in Halo 3.

Location
It is nearby New Mombasa, Kenya, and serves as the crossroads for railway lines between three Kenyan cities, including New Mombasa and Nairobi.

Topography
Voi is described in its concept art to be a "worker town", and is filled with mechanical factories and shoreline buildings. Nearby is the remains of the New Mombasa Orbital Elevator from Halo 2, which is scattered across the level. Voi in the mid 26th century is situated around a man-made lake. As a result of the global warming period of the 21 century, the snow melt that supplied Voi with a water supply died off, creating a major water shortage. It was decided to construct a man-made lake to store water from the remaining mountain runoff, this lake was built at what was then the western edge of Voi. By now Voi has grown to such a size that it almost totally surrounds it and a ferry service was constructed to carry cargo and people across the lake. One of the ferries is encountered stranded on a beach during the level Storm. Along with that, the Voi River still runs through, providing easy transport up and down the river for the industry.

Halo 3
Three successive Halo 3 campaign levels - Tsavo Highway, The Storm and Floodgate, take place in or around Voi. The multiplayer map Foundry is set in a Voi warehouse.

Tsavo Highway , the third campaign level, takes place along the road to Voi, as does most of the following level The Storm in which the Master Chief must defeat a Scarab.

The Storm deals mainly with the character assaulting Covenant forces entrenched in Voi.

 Floodgate deals with clearing the Flood from the city, although the city is eventually glassed by Covenant Separatists.

Battle of Voi
The Master Chief arrives in Voi via Tsavo Highway and joins up with the Arbiter and a large group of Marines. The Battle of Voi begins with the UNSC attacking entrenched Covenant Loyalist forces. Together they destroy many Anti-Air Wraiths, a Scarab, and a Covenant anti-air gun. With the anti-air forces destroyed, Lord Hood's ships begin to attack the High Prophet of Truth's Forerunner Dreadnought, until Truth activates the portal to the Ark and escapes. After this, a damaged Covenant Cruiser crashes in at the western edge of the city. This ship is full of Flood, and the Master Chief and the Arbiter begin to fight this new threat. They start to move to the downed Cruiser, hoping to destroy it and contain the Flood. As they near the Cruiser, a Covenant Separatist ship arrives, led by Shipmaster Rtas 'Vadum. The ship, the Shadow of Intent, deploys Elite ground forces to assist the humans. The humans learn that the Separatists are looking for Cortana, who is supposedly aboard the Flood Cruiser. Separating from the Arbiter, the Chief goes aboard the Cruiser. What he finds is not Cortana, but a damaged message left by her. As he is inspecting it, 343 Guilty Spark arrives to repair "Cortana." All human and Elite forces retreat to the Shadow of Intent as 'Vadum glasses Voi, therefore destroying all Flood in the vicinity.

Trivia

 * The town of Voi was actually first seen in the Halo 3 Announcement trailer more recently to the launch of the game, the only part seen was the billboard on fire (Floodgate) and Master Chief emerging from the destroyed elevator out of Crow's Nest which wasn't near Voi at all.