Mammoth is one of three scenarios created by an engineer named Jeff Head and released in the "Best of the Net" pack 2 folder in Fantastic Worlds and the Multiplayer Gold Edition of Civilization 2. The other two scenarios in this folder that were created by Jeff Head are USA 2010 and Paradise.
Each of the three scenarios takes place in the near to distant future. They all share a central, alternate timeline beginning with the USA 2010 scenario. In USA 2010, following a financial collapse in 1999, the United States is taken over by a Fundamentalist Christian dictatorship by the year 2010. The rest of the world forms a "New World Order" to contain the military expansion of the United States into Canada and Mexico.
The Mammoth Scenario takes place farther into the future, where several civilizations have colonized the eponymous planet, and are, for the first time, able to expand beyond the boundaries of their initial settlements following the abrupt dissipation of harsh solar activity that had previously limited their expansion.
The Paradise Scenario has a similar premise to the Mammoth Scenario, except instead of colonizing the planet with spaceships, humans are teleported to the "Paradise" planet on a one-way trip that only transports organic matter for some reason. The resulting absence of machinery and technology results in a reversion to ancient civilization on the other side of the portal.
USA 2010 and Mammoth share the same tech tree, city improvement tree, wonder tree, and unit tree, which begin with mildly futuristic and contemporary technologies while ending with truly alien developments. The Paradise scenario contains a highly truncated version of these trees in order to make room for all of the ancient, renaissance, and industrial developments that are absent from both the USA 2010 and Mammoth scenarios.
Unfortunately, starting a new game with the Mammoth scenario invariably leads to the game crashing (Multiplayer Gold Edition). This problem can be partially overcome by starting a new Mammoth game, saving it in the same directory as standard games, and then loading the save file from the standard game folder, allowing you to view certain scripted events intended for the Mammoth scenario without crashing the game.
In addition to the use of original audio files and custom designed graphics, all of these scenarios make use of sprites taken from Sim City 2000 for certain units and city icons.
Recurring themes in these scenarios include hostile terrorists, aggressive nations, militarism, xenophobia, and extremely advanced technology and weapons. For some reason, nuclear weapons are not available in USA 2010 or Mammoth. Instead energy field manipulating force fields and hovercraft play a primary role in the military domain.