Gemini

Gemini is a Halo 2 multiplayer level, added to Halo 2's Maptacular Pack, based on the level Duality from Marathon, set on High Charity. It is one of the smallest Halo 2 maps.

Summary
It is considered as being the Prophet's retreat. It is somewhat of an unusual level, as it consists of an open outside area and closed-quarter inside area. Teleporters can warp players up to two small balconies on the top of the inner area. Another teleporter warps players to the outside and back. There is a wide array of weapons from close ranged Brute Shots and the Energy Sword, to Carbines and a Beam Rifle. Also, an Overshield can be found in front of the giant Prophet statue. Another interesting feature is the addition of doors; the doors make you feel like you're in the levels Gravemind and High Charity. It is pretty rare to find classic doors in a multiplayer level like this; Gemini is in fact the only multiplayer map that features these doors

The statue of the Prophet in about the middle of the map is probably a founder of the Covenant and what appears to be a natural tree. Outside, the map features 5 Covenant Phantom docks and what appears to be a natural tree. In the background behind the Phantom docks you can see the Forerunner Dreadnought that the Prophet of Truth used on the Halo 2 level High Charity to get to Earth. The ship is also the last time you see the Master Chief in the game.

It is possible to get below the level and explore the city. You can see how, either here or here

Territories

 * Lower Level
 * Upper Level
 * Walkway

Trivia

 * Some believe the symbolism of the Prophet and the Halo ring represents the Prophets' role as providers of the Holy Rings to the Covenant.
 * Gemini can be spotted in Campaign mode in Halo 2. On the level Gravemind, when you exit the High Council Chamber and you get near where the Arbiter was tortured, look to the left, and in between the two giant towers with the eye-shaped purple design, you will see a smaller tower with the exact shape as the Gemini map.
 * There are two spires that appear in the levels Gravemind and High Charity, but the player is unable knock them over.
 * Except for Cold Storage, it is the only level in the Halo series with blue teleporters in place of green ones.
 * Outside looking down over the edge of the platform it is possible to get down and run around on the spikes far below
 * The map's name and description are a reference to the Marathon multiplayer map Duality, on which Gemini is based.