New Mombasa is a fictional island-city in Kenya, Africa in the video game Halo 2.
The massive man-made island sits offshore from "Old" Mombasa, Kenya and is connected to the mainland by large bridge. The focal point of the city is a central tower that rises into the heavens and serves as the tether point for a space elevator.
Near the beginning of Halo 2, the Master Chief arrives in Old Mombasa to help the UNSC liberate the city from Covenant occupation forces. After fighting through the crowded streets of the Old City, the Master Chief crosses the beach to get to the bridge to the New City. After destroying the Covenant Scarab, the course of the battle turns and the High Prophet of Regret flees from Earth in his flagship. The hyperspace rift that the ship opens subsequently destroys most of the city.
There is speculation that Mombasa held some significance to the Forerunners which is why the Covenant attacked the city. The fact that the Prophet of Regret was able to jump straight to Installation 05 afterward indicates that something must have been found while in Mombasa, because the location of the Halos were a mystery to the Covenant.