Arkham Horror is an Adventure Board Game based on H. P. Lovecraft's Cthulhu Mythos and taking place in the 1920s. It was designed by Richard Launius in 1987 for Chaosium and was revamped and re-released by Fantasy Flight Games in 2005. The players must cooperate as a handful of investigators trying to prevent the awakening of an Ancient One with the fate of the city of Arkham, and sometimes the whole world, in the balance. The investigators will collect ordinary and magical items, explore forgotten or forbidden regions of the town, battle monsters, enter alien worlds, and (per the setting) go gibbering insane in the process.
The game is fairly complicated and features a staggering amount of cards, markers, and counters. Three decks of standard size Ancient One cards are used for random encounters and events. Nearly a dozen decks of smaller sized Investigator cards track the possessions/status of the players. There are fistfuls of cardboard counters for health, sanity and money, monster markers, and other miscellaneous tokens. Success or failure is determined by a pool of six-sided dice; every roll of five or six counts as a success, but modifiers can add or subtract from the dice pool for your roll and difficult tasks can require multiple successes.
Investigators are the player characters. Each investigator has scores for stamina and sanity, some set and random starting items, and a special ability such as healing or extra income. They also have a collection of linked and adjustable attributes, so raising one stat will lower its counterpart. For example, you can move faster at the expense of stealth to speed through the town on one turn and next turn change scores to sneak past the monster guarding your destination at a snail's pace.
The Ancient One is a powerful, alien monster featured in the Cthulhu Mythos, including Cthulhu himself. Each Ancient One has a character sheet akin to an investigator which includes special rules that modify the game as a whole (such as ongoing harmful weather), rules modifying its favorite monsters, and combat stats should it awaken. One is randomly drawn to be your antagonist for the game and the players ultimately race against time to prevent its awakening. Almost every turn a counter will be added to the doom track. When full, it awakens and the investigators have one last chance to defeat it. There are very few ways to slow the doom track down and many to speed it up. It also serves as a health meter during the fight. Ancient Ones are horribly powerful in combat, often resistant or immune to forms of damage and usually able to kill unlucky investigators who fail to meet specific requirements before combat even begins.
The game is played on a large board depicting Arkham city (no, not that one) and divided into neighborhoods with multiple locations within them. Random encounters can occur at almost any location in the game and the encounters range from paranormal horror to mundane accidents. Some areas provide set beneficial effects that allow the players to shop, heal, or learn new skills. On the long side of the board are the other world locations representing alien dimensions like Yuggoth or lost terrestrial regions like the Plateau of Leng. Investigators must brave the other worlds to seal the portals; while they generally don't encounter monsters while doing so, they often face other threats to their health and sanity.
Mythos cards control the flow of the game. One is drawn at the start of each turn. A mythos card will open portals, move monsters, reveal clues, and activate other events that can hinder or help the investigators. Portals open in unstable locations and release monsters. Having too many open portals can awaken the Ancient One early. Portals can only be closed after slowly exploring the other world linked to it, and in most cases, they can be reopened later in the game. Every new portal brings at least one new monster to the city. Monsters move randomly based on a series of black and white arrows on the game board and the mythos card drawn, and some also have special movement rules such as being able to fly. While you can attempt to evade monsters with stealth, they must ultimately be dealt with; having too many monsters in play is not only dangerous and obstructive, but will advance the terror track. The terror track measures the level of fear in Arkhams residents, and the higher the track advances, the fewer services and allies will remain in town.
Eight Expansion Packs have been produced for Arkham Horror so far. Four of them are larger expansions with new boards representing other cities in New England, a host of new investigators, Ancient Ones, and monsters. They're also almost as expensive as the original game. The four smaller expansions feature a few new rules, monsters, and additional cards in the base game. A major new rule spanning the expansions is the addition of the Herald, a powerful monster acting against you and serving as the Ancient One's Dragon. A later expansion adds Guardians, which are beings and/or organizations supporting (or at the very least being on roughly the same side as) the Investigators.
- Exhibit items: Similar to unique items but can only be received through random encounters.
- Barred from the neighborhood: A combination of offending the locals or a traumatic experience on your end prevents you from entering locations in a given neighborhood.
- Benefits and detriments: Some new special effects that can be attached to your character.
- Dual-color Gate cards: Double-duty random encounters for other world events.
In 2011, a revised edition was released. Among the changes:
- The Exhibit Items, Spells, Allies, Benefits, and Detriments had their effects overhauled.
- The Barred from Neighborhood mechanic was replaced with Patrol markers.
- The Ancient Whispers marker and Exhibit Encounter deck were added to provide an additional and more certain method of obtaining Exhibit Items.
- The inclusion of the Dark Pharaoh Herald.
The Dunwich Horror: Large expansion. In a rural town outside of Arkham, a family of sorcerers have created an abomination that threatens mankind. Adds eight investigators, four Ancient ones, and two other worlds.
- The Dunwich Horror: An extremely powerful monster that can be summoned during the game. The Horror can randomly advance the doom track and has randomly drawn abilities and combat stats per battle.
- Injury and madness: Being reduced to zero stamina/sanity now has a lingering effect. Injured/insane investigators can be retired to allow the player to draw a fresh character.
- Conditions: These are ongoing effects that have "toggle" conditions and can activate/deactivate continuously during the game.
- Stalker monsters: Sneaky monsters which can directly pursue nearby investigators, even ignoring the boundaries that limit monster movement in the process.
- Tasks and missions: Lengthy side quests may be taken to gain rewards, missions also require sacrifices to complete.
- Vortices: Special locations in Dunwich of dimensional instability. Monsters will enter them to advance the terror track and to summon the Dunwich Horror.
- The King in Yellow: The play is performed in three acts; reaching the third act ends the game. The first two will randomly occur based on new mythos cards unless the investigators pay the cost of preventing it.
- Magical effect cards: These keep track of ongoing spells cast on your investigator.
- The Herald rules were introduced in this set. The Herald changes the game much like having a second Ancient One in play. The first Herald, the King in Yellow, forces you to choose between adding Blight characters into play or advancing the doom track under certain conditions.
- Blight: These characters have gone mad from the play and serve as anti-allies to hinder you.
- Spawn monsters: These are monsters that only enter play under specific conditions.
The Kingsport Horror: Large expansion. Mythos-related problems are starting in nearby Kingsport, however, there are friendly powers intervening for humanity. Adds eight investigators, four Ancient Ones, two other worlds, and two new heralds.
- Guardians: Three benign entities are aiding mankind.
- Aquatic monsters: These monsters can directly move from aquatic locations to attack investigators.
- Elusive monsters: These monsters try to avoid investigators
- Rifts: These are mobile Gates that might open during play. Once open they move across the board spawning monsters and possibly advancing the doom track.
- Epic Battle rules: These are randomly drawn events that change how the battle against the Ancient One plays.
The Black Goat of the Woods: Small expansion. The cult of Shub-Niggurath is rising in power and must be stopped.
- Corruption: Exposure to the Mythos now causes horrible mental and spiritual decay to investigators.
- Gate bursts: Gates that have been sealed can be forced open again. This, however, doesn't advance the doom track.
- Cult membership: You can infiltrate the One of the Thousand Cult and experience new encounters.
- Difficulty levels: optional cards give guidelines on altering the difficulty of the game.
The Innsmouth Horror: Large expansion. This town is directly under the control of Mythos forces and its Deep One masters are making their move for power. Sixteen new investigators, eight new Ancient Ones, two new heralds.
- Innsmouth: The town is an enemy base and investigators will have to evade the police while exploring the area or suffer harsher consequences.
- The Innsmouth Look: The town is home to human/Deep One hybrids, possibly including the investigators!
- Deep One uprising: The Deep One conspiracy in Innsmouth is represented by a new countdown track. If the track fills, their efforts have succeeded and the Ancient One awakens independent of the doom track. The investigators can slow the uprising track by alerting the FBI.
- Personal stories: Investigator backstories now come into play with personal goals to meet.
The Lurker at the Threshold: Small expansion. It's realized that the portals opening through Arkham are extensions of Yog-Sothoth, and it must be confronted to save the city.
- Dark Pacts: Your investigator can make deals with the Lurker for power and aid. Until the Lurker decides to collect on your debts.
- Relationships: Investigators now draw cards that give shared background and benefits with another player.
- New Gates: Gates will have new special abilities to spice things up; from movement to sharing other worlds, to advancing the doom track.
Miskatonic Horror: Large expansion. A discovery at Miskatonic University has created new mysteries concerning Arkham's dark days. Unlike other large expansions it doesn't add a new board, new rules, and new features to the game, rather it builds on the additions from other expansions by adding more cards to the pools (such as new exhibits and cult encounters).
- Institutions: One new feature is gaining the help of "friendly" (at least non-Mythos) organizations.
Currently, Fantasy Flight has switched from expansions to producing spin-offs. Among them are:
- Mansions of Madness: Players investigate an Old, Dark House (one of many possible ones) while one player designated as the Keeper controls the opposition. Sort of a lite-version of roleplaying Call of Cthulhu. Has so far received two large expansions. Forbidden Alchemy introduces a new puzzle type as well as three new scenarios with a Mad Science angle. Call of the Wild features five new scenarios with an outdoors locale as well as non-linear gameplay. There are also six single scenario expansions: Season of the Witch, The Silver Tablet, Til Death Do Us Apart, House of Fears, The Yellow Sign, and The Laboratory (the last one requires Forbidden Alchemy). The second edition of the game introduces a mobile device app which, among other things, eliminates the need for a Keeper player. The box of this game states the app is required, whereas with the base game it is only a suggestion.
- Elder Sign: A Dice-based game where you complete adventures at a Museum of the Strange and Unusual to gain the needed amount of Elder Signs to prevent an Eldritch Abomination from awakening. Essentially a scaled-back version of Arkham Horror. The shortest of all the games, with average playtime around 45 minutes. Currently has four main expansions and a POD mini-expansion: Unseen Forces, which brings many new ancient ones and investigators to the game, Gate of Arkham, which has the action spill out into the greater Arkham area, Omens in Ice, which revolves around an expedition to the frozen wastes of Alaska, Omens of the Deep, which involves a voyage around the South Pacific, and Grave Consequences, a small Print-On-Demand expansion that adds three new gameplay features: Phobia, Epitaph, and Epic Battle cards.
- Eldritch Horror: Involves investigating sinister happening on a globe-trotting scale, with a definite Indiana Jones-vibe to it all. Definitely the closest to the original game, but here the focus lies in solving "Mysteries" (though closing gates is still important). While still large and epic, it is more streamlined and fast paced compared to Arkham Horror, with average playtime at 2-4 hours (compared to 4+ hours). Has received several expansions, adding all of the characters from the game.
- Arkham Horror: The Card Game: A living card game using many of the same characters and concepts. Unlike the usual LCG format, the game is cooperative with players building decks to defeat a scenario where threats come from an "Encounter Deck." Multiple expansions have been announced.
Fantasy Flight has also started publishing tie-in novels, including two trilogies:
- The Dark Waters Trilogy by Graham McNeill
- Ghouls of the Miskatonic
- Bones of the Yopasi
- Dweller in the Deep
- The Lord of Nightmares Trilogy
- Dance of the Damned by Alan Bligh
- The Lies of Solace by John French
- The Hungering God by Alan Bligh and John French
- Feeders From Within by Peter J. Evans
- The Sign of Glaaki by Steven Savile and Steven Lockley
A third edition was released in 2018.
Arkham Horror can be found here. Fantasy Flight gives outstanding support to the game, including .pdf files of all rulebooks, new Heralds and investigators, and rules for tournament/league play.
Arkham Horror shares many tropes with the greater Cthulhu Mythos. The board game directly features examples of:
- A.K.A.-47: Most of the guns go by generic names such as ".45 automatic" or "rifle". The exception being the tommy gun, and "tommy gun" is technically only a nickname.
- Artistic License History: Minor, easily missed one, but should be noted anyway. One of the Arkham Asylum encounters in Innsmouth Horror has you sneaking into a finger-painting session. Finger-painting is indeed used as a component of mental therapy at times, so that's done right. The problem? Art therapy in general dates only to the late 1940's, with finger painting as a later addition to the milieu. Finger painting itself dates to prehistoric times, but it wasn't part of art education until the 1930's.
- Asskicking Equals Authority: If you kill enough monsters and/or seal enough gates, you can be appointed deputy of Arkham.
- The Atoner: Diana Stanley, the redeemed Cultist. She's the mole in the Silver Twilight Lodge and is trying to stop them from within, giving her bonuses as the doom and terror tracks increase.
- Ax-Crazy: Most cultists are after power and favor from their Ancient One. Cultists of Azathoth serve a mindless, universe-ending patron and have nothing to actually gain from it.
- Bedlam House: The infamous Arkham Asylum. The original Arkham, not that other one.
- BFG: The elephant gun, a Real Life example, and a powerful physical weapon in the game. Real elephant guns were frequently custom-made firearms, thus in-game you have to pay every time it's used to refresh it — even the flamethrower can be refreshed at will!
- Big Bad: Whatever one of the Old Ones or Outer Gods gets chosen during the prep phase is the overall main antagonist.
- Born Unlucky: Rex Murphy. You start with a Curse as a result.
- Boss in Mook Clothing: The titular Dunwich Horror. If you can't prevent its arrival, then a seemingly normal monster tile is added to the game. One with a laundry list of special rules. The Dunwich Horror has tons of health, can advance the doom track, and a deck of cards that randomize its combat stats, drawn after you enter combat with it. On one turn, it takes half damage and destroys all your gear; on the next, it has no special resistances but instantly kills you. Defeating it gives you any card you wish as a reward.
- Broke Your Arm Punching Out Cthulhu: You can beat him, for now, but how many investigators went mad or died in the process?
- Canine Companion: Duke. He's good for your sanity.
- Cast From Sanity: Many spells have a sanity cost to play, as does the use of Elder Signs to close and seal planar gates; in the Cthulhu Mythos, that sort of thing draws on higher orders of reality than the human mind can comfortably process — like the ones the Eldritch Abominations come from.
- Cat Girl: Bast, the cat-headed Egyptian goddess who serves as a guardian in Kingsport.
- City of Adventure: Arkham, home to the famous Miskatonic U., a number of dangerous cults, and many eldritch locations. With expansions, Arkham also plays home to Brown Note plays or cursed exhibits.
- Classy Cat-Burglar: Ruby is an ally who improves your sneak and gives you a unique item from her haul.
- Claustrophobia: A madness that can afflict an investigator, causing sanity loss if the victim enters certain locations.
- Combat Medic: Doctor Lee. Subverted if playing with the personal stories addition from Innsmouth, as killing too many enemies lowers Lee's maximum sanity.
- Continuing Is Painful: Losing all your Stamina or Sanity points doesn't end the game for your Investigator, it just sends them to the hospital or asylum, respectively. However, they lose half of their items and Clue tokens. In later supplements, you can opt to take an Injury or Madness instead, but these cripple them for the rest of the game.
- Cool Gate: Portals are more horrifying than cool, though.
- Crowbar Combatant: A decent weapon that can be discarded to attempt some breaking and entering for common items.
- Cult: Your human opponents are members of the cults implied to be responsible for the whole mess. The specific cultist monster is often modified by the Ancient One in play with anything from having unlimited numbers to advancing the doom track if killed.
- Damage Reduction: Seen in different forms through the game. The mobster Michael McGlen features it as his ability, and a few spells and unique items allow for it, as well as the common food.
- Deal with the Devil:
- The Lurker at the Threshold offers these, giving power to the investigator bold enough to claim it.
- The Dark Man of Wizard's Hill is a very helpful individual, but eventually the debt will come due...
- Death from Above: Without an adjacent investigator to attack, a flying monster is allowed to move into the sky location. Once in the sky they are allowed to swoop down on an investigator in any street location.
- Death Is a Slap on the Wrist:
- Being reduced to zero stamina or sanity sends you to the hospital/sanitarium. You will lose half of your items and clue tokens, but you get to choose and you round down. If you somehow lose both, on the other hand, you get devoured...
- With the Dunwich expansion, you can even get around the item/clue loss by accepting, as appropriate, an Injury or a Madness. For many players, the nuisance supplied is more than outweighed by the kept items and clues (especially the clues). Just... be careful about taking multiples, since if you're anyone other than Rita Young, getting a duplicate of an Injury or Madness you already have results in your devouring.
- Devour the Dragon: Rhan-Tegoth likes to eat his cultists.
- Did You Just Punch Out Cthulhu?: You can literally do it. (To Cthulhu, at least, and to most of the other possible Eldritch Abominations as well, with the notable exception of Azathoth.) You're gonna have a hell of a time doing it, though. One expansion has encounter cards where you fight an Ancient One single-handed. And, yes, one of the ones you fight is Cthulhu.
- The Dragon: A Herald is an eldritch being directly trying to summon the Ancient One and working against the players. Adding a Herald to play is akin to adding a secondary Ancient One, as they have a major impact on the game and add many new challenges.
- Dream Land: The Dreamlands are one of the other worlds you can visit. By most other world standards, they're a very nice place.
- Drop the Hammer: The sledgehammer, natch; it thoroughly crushes enemies by giving both combat and fight bonuses and reducing their toughness.
- Dual Wielding / Guns Akimbo: Can be done, if the weapons or spells in question only require one hand each. Two-handed weapons are more powerful, but you can only use one at a time.
- Dump Stat: The dump stat can change during the course of the game, but it's always risky. Each stat is inversely linked with another; thus, for instance, raising your Fight will lower your Will, and you can't kill the monster if just seeing it drives you insane. Luck of the draw and strategy factor heavily in Arkham Horror; having the right items can mitigate the risks of having a dump stat, and you can change it as the situation demands.
- Dungeon Bypass: There are a few methods to skip turns spent exploring the other world; the sooner you escape, the better your chances of sealing portals and maybe winning a game.
- Egyptian Mythology: Bast, the cat goddess, serves as one of the guardians. For a price, you can play Kind Hearted Cat Lover and feed strays to receive her blessing. Her blessing regenerates stamina or sanity each turn and protects you from being devoured.
- Eldritch Abomination: Your many opponents.
- Eldritch Location: The other worlds.
- The End of the World as We Know It: Lesser Ancient Ones like Yig can probably only destroy Arkham itself. Great Cthulhu could end the world. Yog-Sothoth and Azathoth are more than capable of destroying the earth, Azathoth to a degree that the game ends with no boss battle if he awakens.
- Enemy Mine: It's possible to have a group of investigators containing a federal agent, a gangster, a rookie cop, and a bootlegger. And have one of them become deputy of Arkham. Presumably, the threat of the Ancient One dwarfs petty human crime.
- Energy Weapon: The Yithian rifle. It feeds on your Focus to refresh.
- FaceHeel Turn:
- The "Joining the Winning Team" mission requires you to sacrifice allies to betray the other players and win the game for yourself.
- Likewise, when fighting Nyarlathotep, you may get the chance to join him and betray the other investigators.
- Fighting a Shadow:
"It was then that I remembered a terrible thing. Nyarlathotep had a thousand faces with which to battle us — all at once if he so chose."
- Nyarlathotep in spades. He's the Outer God who directly interferes with man and has "a thousand" forms. He's simultaneously an Ancient One, a herald, at least five separate monsters with the base game, and possibly ten with all expansions.
- Yog-Sothoth as well: Ancient One, Herald (the Lurker at the Threshold), and he is every gate in the game.
- Final Boss: The Ancient One is this. It's possible to win without having to fight it, but letting it awaken and then kicking its ass is also a victory condition. Just don't try that on Azathoth, and for other Ancient Ones, not only is victory going to be quite unlikely, but even if you do win, it'll be at great cost.
- Fire-Breathing Weapon: A flamethrower was added in the Dunwich expansion.
- Giant Spider:
- Leng Spiders; the small ones are pony-sized.
- Atlach-Nacha, the horrifyingly-powerful Ancient One and King Mook to the aforementioned Leng Spiders.
- Guns Akimbo: Anyone, if you have two one-handed weapons. Joe Diamond, Jenny Barnes, and Tony Morgan have it on their character portraits.
- Half-Human Hybrid:
- Deep One Hybrids are monsters from Innsmouth, men with horrible inhuman features. Investigators in Innsmouth run the risk of drawing Innsmouth Look cards and discovering that they too are hybrids.
- There are also two investigators, Amanda and Silas, who are already known to be hybrids. Whether or not they discover this fact affects how their personal stories go.
- Hardboiled Detective: Joe Diamond. He was even given this assignment by a classic dame.
- Helpful Mook: Nightgaunts, servants of the alien and somewhat benevolent Nodens. When you lose a battle against them, they drop you into the nearest gate. This can cause you to explore other worlds faster or get to gates that are otherwise blocked.
- Heroic Sacrifice:
- The "For the Greater Good" mission involves getting your investigator devoured to win the game for everyone else.
- Tommy Muldoon, the Rookie Cop, benefits other investigators if he is sacrificed as quickly as possible.
- Silas Marsh can perform a heroic sacrifice (defying his Tomato in the Mirror Half-Human Hybrid heritage) to seal a gate.
- Hobos: "Ashcan" Pete.
- Holy Hand Grenade: Holy water is a one-shot magical weapon.
- Homage: William Yorick the Gravedigger is a homage to Hamlet. His background is that of a would-be Shakespearean actor turned laborer to make a living and his personal story references lines from the play as titles, in particular his failure being called "Alas, Poor Yorick".
- Hot Librarian: Mandy Thompson, the researcher, is quite pretty, shows her cleavage, and has some of the nicest investigator art.
- House Rules: The Fantasy Flight site includes semi-official house rules from the game's creator Richard Launius. In addition, there are investigator sheets for Gabe and Tycho from Penny Arcade Adventures, with Annarchy as an ally.
- Hyperactive Metabolism: An interesting variant: food does not function as a healing item, it instead reduces stamina loss.
- Immune to Bullets: It depends on the monster. Some are as fatally allergic to bullets as people, others will eat lead and then you as dessert.
- I Need a Freaking Drink: Whiskey helps reduce Sanity loss.
- Killed Off for Real: Being devoured. Generally, this only happens if you're quite unlucky in an encounter or fighting the Ancient One.
- Ley Line: The ley line map allows an investigator to circumvent environmental effects caused by Mythos cards.
- Lizard Folk: Serpent People are borrowed from Robert E. Howard's Thurian Age, and cultists of Yig are actually disguised serpent priests.
- Loads and Loads of Rules: The game has rules allowing you to fight monsters, cast spells, go crazy, go shopping, get lost between dimensions, go crazy, join the police, watch the stores close as people leave town, and go crazy before being eaten by an alien super-being. The expansions add more rules to the game to boot, including adding a Dragon to work against you or allowing for pacts with the monster.
- Lovecraft Country: The game's setting, of course.
- Lovecraft Lite: It is perfectly possible, though difficult, to seal or defeat the ancient one with no one going mad or dying.
- Luck-Based Mission: Quite a few of the personal stories are like this. The consequences for losing can be anywhere from fatal to borderline nonexistent.
- Luck Manipulation Mechanic: "Clue Tokens" represent various bits of Mythos-lore the characters have learned through their combing the city. Spending a clue token after a die roll lets you roll an additional die, and you can continue to roll as long as you have tokens to spend. Some Skills even add 2 dice instead of 1 per token to certain kinds of rolls.
- The reason why Mandy Thompson is so broken is that she lets 1 investigator per round re-roll all failed dice.
- Lucky Rabbit's Foot: A common item that is exhausted for a +1 luck bonus.
- More Dakka: The tommy gun.
- Nintendo Hard: Just how difficult the game is depends a lot on the Elder God in play, the players' skill levels, and a good deal of luck. No matter what, it's generally very difficult to actually win.
- The game itself without any expansions is not terribly difficult once you get used to it, but the expansions make the game considerably more difficult, mostly by adding an additional task that the players must work at to prevent the Ancient One from awakening prematurely. The difficulty varies by expansion; the earlier expansions were not too bad, while other ones, such as Innsmouth, make winning the game considerably more difficult, and sometimes you will lose in a manner which is almost completely unavoidable.
- Not-So-Harmless Villain: Azathoth is the Idiot Sultan, incredibly difficult to awaken and unhelpful toward those trying to wake him up. On the other hand, if he does wake up, it's The End of the World as We Know It. In the Innsmouth expansion, he becomes even more dangerous, as the rise of the Deep Ones can, in fact, wake him up.
- Obvious Rule Patch: Later versions of the rules specifically tell you to redraw if the initial draw is one of several card types likely to render the game unwinnable before it even starts if it's the first card drawn.
- Oh, Crap!: The aptly named mythos card, "No One Can Help You Now", which prevents gates from being sealed.
- One Stat to Rule Them All: Averted. Fight and Lore are arguably the most important stats in the main aspects of the game; combat, spells, and gate closing. However, any stat can be called on during a random encounter, so focusing on your Fight/Lore can ultimately cause more harm then good.
- Orphan's Plot Trinket: The orphan starts with an Elder Sign.
- Persona Non Grata: Part of what causes the "barred from the neighborhood" effect, preventing you from entering the locations in a neighborhood.
- Piñata Enemy: Mi-go are fairly weak and killing one gives you a unique item.
- Plot-Triggering Death: Many of the characters' backstories have this as a motivation. Examples include George Barnaby's wife, Kate Winthrop's professor, Michael McGlen's friend.
- Popularity Power: Cthulhu is the Face of the Band when it comes to Lovecraft's pantheon. He's also listed as That One Boss.
- Power Creep: The expansions introduce bigger and badder bosses and monsters, heralds as TheDragon, and more ways for the Ancient One to Awaken. To compensate, stronger investigators, items, and skills are introduced.
- In the regular game, most investigators have abilities like reducing damage, drawing extra X cards, or being able to restore Sanity and Health when in the same neighborhood. Expansions introduce investigators with abilities such as being able to bypass horror checks, letting other investigators use your clue tokens, and making it much much easier to seal gates.
- Slightly downplayed in that Cthulhu, Mandy Thompson, and the Elder Signs (one of the most powerful BigBads, investigators, and items) are all part of the regular game.
- The Professor: Professors Armitage and Walters.
- Race Against the Clock: Trying to seal all the portals before the doom track fills and the Ancient One awakens.
- Rag Tag Band Of Misfits: Very likely the player's investigative group. It's easy to have a group made up of a crooked Politician, a Federal Agent, a Street Urchin, and a Cook.
- Random Number God: Perhaps the real indescribable, eldritch horror in the game. Made more or less forgiving by the "blessed" (successes occur on die rolls of 4, 5, or 6) or "cursed" (successes only occur on a die roll of 6) statuses; a Cursed adventurer is generally screwed until they can shake it off or otherwise buy their way out of it at the church.
- Rocks Fall, Everyone Dies: Azathoth destroys the world upon awakening. You lose.
- Sand Worm: Dholes are massive, powerful burrowing worms that resist both kinds of damage, will harm your sanity and stamina regardless of rolls, and are just hard-hitting and hard to kill to boot. Chthonians are squid-like burrowing worms that are fairly powerful but their real threat comes from causing earthquakes that automatically damage all investigators in Arkham.
- Sanity Meter: You have sanity points in addition to stamina. Sanity is lost casting spells or seeing monsters, when you lose it all you're sent to Arkham Asylum to recover.
- Screw This, I'm Outta Here!: Every time the terror level rises, someone from the ally deck is discarded signifying people fleeing Arkham as monsters take over.
- Many of the Allies are characters from Lovecraft's stories.
- Several of the encounters at Velma's Diner make mention of the coffee and the cherry pie.
- Socialite: Jenny, the dilettante. She was in Paris before coming to Arkham in search of her sister. She starts with a lot of cash, and her special ability is getting more each turn from her trust fund.
- Solo Tabletop Game: Listed for 1-8 player, solo play is made possible since monsters generate and events happen according to the Mythos deck. Also, the Ancient One has its own character template.
- Squishy Wizard / Glass Cannon:
- Professor Walters. He has decent Speed, Stealth, and Luck scores, but he truly shines in that he has one of the highest Lore skills in the game, ties for the highest innate Sanity points, and his special ability reduces all Sanity losses by 1, saving his Sanity points to allow him to use plenty of books and dual-wield combat spells for extra fun. This is, however, countered by the fact that he has some of the lowest Will, Fight, and physical health stats in the game.
- Similarly, Marie Lambeau has fairly high innate Sanity, starts with 3 spells (for context, most characters start with only one or none at all, and Walters above starts with 2), and has an innate ability that gives her a third hand that can only be used to cast spells, allowing her to use the other two for other purposes. Her second ability is even more powerful, allowing her to instantly remove a doom token from the Ancient One's doom track (and, if she passes her personal story, she can do it twice and learns 2 spells each time she does it). However, she has poor Fight, below average Stamina, and merely average stats in other areas (although her Will is actually fairly high).
- Stage Magician: Dexter Drake, who yearned to discover real magic some day. Unfortunately, he found remnants of the Necronomicon and learned that magic is real and disaster is coming.
- Start X to Stop X: The spell "Call Ancient One." Using this card, you can summon the Ancient One yourself so you can fight it on your terms. (If you do this with Azathoth, you have no one to blame but yourself.)
- Taken for Granite: The petrifying solution is a chemical from The King In Yellow that serves as a powerful one-shot weapon with a hefty combat bonus and ignoring the physical resistance and endless abilities. Amusingly, in the original story it was lifted from, the effect is only temporary.
- Time Bomb: A common item that can detonate 1-3 turns after being placed, killing all monsters and investigators in the location.
- Tomato in the Mirror:
- Drawing an Innsmouth Look card and discovering you are a Deep One hybrid.
- If two gates to R'lyeh are open at the same time, Amanda Sharpe discovers the truth behind those dreams she's been having...
- Tome of Eldritch Lore: You can find famous Mythos books like the Necronomicon in this game. Reading them gives you a chance to learn spells or skills, at the cost of insanity.
- Town with a Dark Secret: Dunwich and especially Innsmouth. The difference being that in Dunwich, everyone is afraid of its secret, and in Innsmouth everyone is part of it.
- Turn Undead: The cross is a magical weapon that only provides a combat bonus against undead enemies. It does, however, always provide a bonus to a horror check. Jim Culver, meanwhile, has a special ability that lets him spend a clue token to auto-defeat any undead foe.
- Unskilled, but Strong: Azathoth is the sleepiest of the Ancient Ones, and has only one special power. That power is to destroy the world.
- Vertical Kidnapping: Nightgaunts will swoop in from above, overpower you, and drop you in the nearest portal. This can be beneficial; they will do this in other world locations and return you to Arkham, then allowing you to close the portal.
- Villain Protagonist: While the monsters & old one are much worse, Michael McGlen's still a mobster working with allies such as a magician, a student, an archaeologist, and a detective.
- Whip It Good: A whip is available as a weapon, and the archaeologist Monterey Jack starts with one.
- Zonk: While most of the cards in the Exhibit Encounter deck from the Revised Curse of the Dark Pharaoh provide an opportunity to gain an Exhibit Item, one of them can result in the top card of the Exhibit Item deck being removed from play automatically.