Gates are inter-dimensional portals that link Arkham city with Other Worlds. In the Arkham Horror board game, gates have begun opening all over the city, stirring evil beings called Ancient Ones from their slumber. The players must band together to close and/or seal these gates if they wish to stop the Ancient One from awakening.
In general, each turn a Mythos card is drawn and a gate marker is placed at a specific location. When the gate opens a monster appears, which begins wandering about the city. Investigators can enter the gate and complete encounters in Other Worlds. After completing enough encounters, the investigator can return to Arkham and close the gate. Closing gates is important, for if too many gates open at once the Ancient One immediately awakens, forcing the investigators to do battle! Closing gates is also important because it is a victory condition - if the players close enough gates they can seal away the Ancient One and win the game.
During the Mythos phase, a Mythos card is drawn that depicts a gate opening at some location. The first player looks in the lower-left corner of the card to see where dimensional forces are assaulting Arkham (this only happens at unstable locations). Depending on whether a gate or elder sign currently exists at the indicated location, one of three things happens:
- Location has an elder sign: If an elder sign token has been placed an the location, nothing happens. No gate opens and no monsters appear. (However, if playing with one of the expansions, the card may specify that a Gate burst occurs, causing the destruction of the elder sign. In this case, remove the token and proceed as if there had been no elder sign present.)
- Location has an open gate: If there is already an open gate at the location a monster surge occurs. The first player draws a number of monsters equal to the number of open gates or the number of players - whichever is greater. These monsters are then distributed as evenly as possible across all open gates (keeping in mind the current monster limit).
- If there is neither an open gate nor an elder sign at the depicted location, a new gate opens.
- The first player places a doom token on the Ancient One's doom track. If the marker is placed on the last available space, the Ancient One awakens.
- The first player draws a gate marker from the stack of unused gate markers and places it face up on the location. Any clue tokens on that location are discarded.
- The first player draws a random monster from the monster cup and places it at the location (if this would bring the number of monsters over the monster limit, the monster is placed in the Outskirts instead).
Gates opening on investigators
If a gate opens on a location that contains an investigator, that investigator is immediately drawn through the gate into the first area of the corresponding Other World. This also disorients the investigator, causing them to become delayed.
During the Arkham Encounters phase, any investigator that enters a location with a gate present is drawn through the gate into an Other World. The investigator moves to the first area (the left) of the Other World indicated on the gate marker. After completing enough encounters and movement in the Other World the investigator may return to Arkham. The player enter Arkham from any location containing a gate to their specific Other World, and places their investigator marker on that area. An explored marker is placed under the investigator to denote that he or she has explored the gate. This marker remains in play as long as the investigator stays at that location - if they leave the location for any reason the marker is discarded, and the investigator must once again make their way through the gate if they wish to close it.
If an investigator is drawn through a gate that appears as the result of an encounter (such as "A gate appears!" or "A gate and a monster appears!"), the investigator is delayed.
Monsters guarding gates
During the first turn an investigator returns to Arkham the investigator does not need to evade or fight any monsters at the gate's location. If the investigator remains at the location on subsequent turns, however, he must evade or fight the monsters as normal.
If an investigator is in a location that contains a gate during the Arkham Encounters Phase and they also possess an explored token earned from exploring the Other World, that investigator may attempt to close the gate. To do so, the investigator must make either a Lore check or a Fight check, using the number printed on the gate marker as a modifier. If the investigator succeeds at this check, they close the gate and take the gate marker as a gate trophy. If the investigator fails their roll the gate remains open, but the investigator may try to close it again next turn if they wish (so long as they do not leave that location).
If an investigator successfully closes a gate they may immediately spend 5 clue tokens to seal it. The player takes a doom token from the unused pile of doom tokens and places it on the location with the elder sign facing up. The gate on that location is now sealed. Sealed gates mean that no further gates can open at that location - if a mythos card calls for a gate to open the gate is ignored.
Sealing gates with an Elder Sign
Elder signs are a specific type of unique item that investigators can use to seal gates. To use an elder sign, an investigator must be in the same location as a gate and have already explored the gate, as per the normal rules for closing gates. Then, instead of making a Lore or Fight check, the investigator does the following:
- Remove 1 sanity and 1 stamina from the investigator sheet. Even if this knocks the investigator unconscious or drives them insane, the elder sign still takes effect.
- The player takes a doom token from the Ancient One's doom track (not the unused pile of doom tokens!) and places it on the location with the elder sign up.
- The elder sign unique item card is returned to the box; it cannot be drawn or used again this game.
Just as with spending clue tokens, the gate is now sealed.
Closed gates and monsters
Closing gates can cause the investigators to win the game:
- If an investigator closes the last open gate on the board and all players have a combined number of gate trophies equal to or greater than the number of players, the players win. Stability is restored to Arkham and the Ancient One slips back into sleep.
- If there are six or more elder signs on the board at any time, the players immediately win. The investigators have managed to seal away the Ancient One and save Arkham (and the world).
When the number of open gates is greater than or equal to the gate limit, the Ancient One awakens. This limit is shown below:
Number of Investigators Number of Open Gates 1-2 8 3-4 7 5-6 6 7-8 5
Lurker at the Threshold Gates
These allow the investigator to enter and explore either Other World. Upon closing a Split Gate, both dimension symbols on the gate are used for returning monsters to the cup.
Gate of Doom
Endless Gates cannot be claimed as gate trophies. They are instead immediately returned to the supply of gates.
Gate of Blood
If an investigator fails a check to close a Gate of Blood, that investigator loses 1 Stamina.
Gate of Madness
If an investigator fails a check to close a Gate of Madness, that investigator loses 1 Sanity.
Moving Gates move as if they were a monster of the dimensional symbol displayed on the gate.
- Only one gate can occupy the same space, with ties resolved by the first player.
- If a gate moves onto a space containing an investigator, they are pulled in as if the gate had opened on that space.
- If a moving gate moves away from an investigator who has explored that Other World, the investigator loses their explored token.
- A gate may only be sealed on an unstable location. Other gates can still be closed, but not sealed.