My eyes delved into the caliginous corner of the room, my brain willing my sight into acute reception, yet I felt my humors becoming viscous as if some primal defence mechanism sought to save me from witnessing an unquantifiable, satanic awfulness. I blinked fervently to clear them, praying that the horror I thought to be there would in fact be no more than an exotic pet, the kinds of which I had read about in Professor Abrams’ diary of his journey through the Amazon swamps. Its form quivered before me as its massed orbs coalesced under its eldritch will and the voices of the asylum’s demented howled in my ears as the edges of my perception rumbled darkly.
Arkham Horror is a co-operative adventure game with storytelling elements. Gates to other worlds are opening across Arkham and spewing forth unspeakable horrors in addition to breaking down the barriers between our world and that of a Great Old Ones. Your goal is to stop this monstrosity from awakening and enslaving/destroying humanity, which you can do either by permanently sealing the gate rifts, closing all the open gates or, if all else fails, defeating the Great Old One itself in battle. Your character represents an everyday individual that senses the doom that leers over humanity and has come to Arkham to investigate and attempt to stop it. Should the Ancient One awaken and the investigators fail to defeat it in the final battle then the players all lose. As part of your investigator’s journey then you will visit the strange places around Arkham and collect clues that you will spend when sealing the gates around Arkham. While investigating then you will meet quirky townsfolk; fight horrific monsters and even experience the wonders and perils of other worlds.
The next I recall is a distant pain as my body drifted away beneath me; I am told the mercy of a passing Good Samaritan found me by a tree; this sullen contusion upon my brow. He brought me back to civilization, a veritable island of good thought, sheltered from the darkness beyond our shores. Can I ever reconcile our haven with the world that lies beyond? That which I glimpsed in what seems like a gorgonic nightmare? For I fear the creature will come for me; in its numerous glittering eyes I saw my own image boring into its malevolence, tempting a demonstration of its terrible justice. I know too much.
Arkham Horror has numerous expansions, though they all fall into either one of two categories: mini expansions that add scenario style theme additions to the standard game, and big box expansions that add an extra board which represents a locale near Arkham that the investigators can visit.
Mini expansions provide an additional themed event that is occurring in Arkham at the same time as the standard game play. Curse of the Dark Pharaoh provides several location encounters and additional events that reflect the presence of a touring cursed museum exhibit that has stopped in Arkham. You can choose whether to mix in the themed scenario into the current decks and just have the events come up in your normal game, or there are usually instructions to keep the events separate and draw from those separate decks more frequently to guarantee you see more of those expansion cards and thus provide a fuller flavour of the scenario you have set up. Mini expansions usually add some additional items, spells and other cards to the standard decks, which provide a more unique experience each time you play as you will receive different items more often.
Big box expansions, as already mentioned, provide an additional board that represents another locale your investigators can travel to. This board functions just like the standard Arkham board in that gates will open there, monsters will roam around and there will be locations where you can find clue tokens and experience encounters like the ones you would in Arkham. Often each board comes with a unique mechanic, for example, the Dunwich Horror board reflects the village of Dunwich and the attempts of Wizard Whately to call the eponymous ‘Dunwich Horror’ into this world. If too many monsters roam the Dunwich board then eventually the Dunwich Horror will be called up, that will continue to add doom tokens to the doom track until the investigators face it in battle, no small feat!
Big box expansions also provide new Great Old Ones to fight, new investigators to play, new monsters to fight and additional cards for almost all the standard decks, but also sometimes include new decks of cards that offer variation features you can choose to include in your standard games with or without playing with their respective board. For example, Dunwich Horror includes Madness and Injury decks that an investigator can draw from instead of losing their clues and items when they go insane/unconscious. They represent permanent handicaps and if an investigator receives too many of the same type then they are instantly devoured.
Overall, it is up to you how many of the expansions you mix in and which additional features you choose to incorporate. Some players choose to mix all the expansions they own together, providing a plethora of new items to discover and encounters to experience, others prefer to include just one or two expansions at a time for a more tightly themed set of events and they will rotate the expansions they own when they want to try something different. Many of the additional cards can mix into their respective decks without any need to remove them when switching which expansions you are playing with. It should be noted that the more additional boards you play with then the challenge required to beat the game goes up considerably as the investigators have so much extra ground to cover in terms of where gates open as well as dealing with each big board’s respective additional mechanics. There are certain compensatory effects put in play to account for the extra ground but the game will still be noticeably harder to beat.
Final note: the Miskatonic Horror big box expansion does not come with an additional board but instead provides numerous additional cards that are designed to add more to the game with each successive expansion you incorporate. It provides more for almost all the decks, including more cards for feature decks that are introduced in the other big box expansions.