Errata: At 11:55 AM EST 01/13/2018, the phrase “front of the back” was changed to “front or the back”.
The Ancients divided space into a hexagonal grid, each tile of which may be empty space or may contain a Stargate along one of its edges. The front of a Stargate always points outward and the back points towards the center of the tile.
If a ship enters a tile with empty space, it passes through freely without changing directions.
If a ship enters a tile with a Stargate, what happens next depends on the direction of travel. If the ship is not flying directly into the front or the back of a Stargate, it is unaffected as it flies through the empty space behind the Stargate:
If a ship flies into the back of a Stargate, it is dematerialized and destroyed:
If a ship flies into the front of a Stargate, the Stargate will automatically dial the Nth Stargate in space (numbered across rows, then down columns, starting at 1) where N is the number corresponding to the letter labelling the most recent tile that the ship flew through (A=1, B=2, etc., wrapping back to the beginning if N is greater than the number of Stargates in space). The ship will then emerge from the front of the Nth Stargate, travelling in the direction that Stargate faces (i.e. out of the tile). For example:
Flying into or out of a Stargate does not constitute flying through that tile, but flying through the empty space behind a Stargate does. (Notice, in this example, that the ship exits the 3rd Stargate, having flown through a tile labelled C immediately before entering the Stargate.) If a ship that has not flown through any tiles enters a Stargate, Stargate 1 is dialed.
The Ancients left behind a map, which unfortunately has been heavily damaged by the eons. We know their letter code also indicated Stargate placement and orientation, with one letter representing each of the six orientations and the remaining twenty letters representing empty space. Unfortunately, the code itself has never been found. (The illustration above is purely exemplary and does not necessarily reflect the Ancients' code.)
Instead, we have sent six probes (marked here in colors) into space to explore. Some were lost (either dematerialized or trapped in a loop), but most emerged elsewhere in space. Prometheus is standing by (its current location marked here in white), ready to explore the unknown.