update (22 Nov 2016): The new modern bus system in Windhoek ("Move Windhoek") has been suspended with immediate effect due to "some operational challenges that the City is currently addressing".
The City of Windhoek is set to introduce a new modern bus system on 14 November 2016, which will replace the old bus routes (direct buses). The new bus system (Move Windhoek bus lines) will consist of 14 bus lines that will provide a frequent bus service between Windhoek's suburbs, such as Katutura, Goreagab, Havana, Okahandja Park, Kabila and Otjomuise, and the City Centre, as well as between the surrounding suburbs, such as Auasblick, Rocky Crest and others, and the City Centre. In addition, the City of Windhoek will also introduce local bus lines operating between Soweto Market and Wernhill Park, from Goreagab and Otjomuise and from Wernhill Park to Eros, Klein Windhoek and Avis as well as from Wernhill Park to Olympia, Suiderhof and Auasblick.
During the transition period, officials will be at all key bus stops in Katutura during the morning hours to direct customers to the relevant busses. Customers can interchange from one bus line into another at Wernhill transit facility in Windhoek's City Centre without paying again; therefore customers are required to retain their receipts as proof of payment. (via City of Windhoek media briefing dated 28 October 2016)
Tickets cost 6 NAD per person (cash) and 5 NAD per person if you are using the MoveWindhoek Smart Card.