Eldritch is a randomly generated first person action adventure game and contains a number of places to explore. The explorer enters these places via several Strange Books located in the Library.
The Library
The library spawn area, including the Mirror
This is the hub of Eldritch. It is filled with books that offer clues as to the nature of the game world. There are no Denizens in the Library's three floors, but not every square is accessible, and the top floor can be closed off completely.
There are three glowing books which allow you to access the three main worlds of the game and a Chest in which you can store and access "artifacts" which act as the game's form of currency. The "Mountains of Madness" expansion adds a fourth book leading to the eponymous Antarctic mountains. A final fifth book leads to the Asylum challenge level.
The Mirror allows players to customize their appearance, although they will not be visible at any other point in the game. Desk lamps may be shut on and off. Fruit will grow on saplings at random throughout the Library.
The Library's layout seems to be randomly generated outside of the usual areas and features. In the current game build the Library is locked to a single layout at the start of a run, but it is possible to reveal other squares using the Pickaxe or Revolver and Destruction Amulet combo, sometimes uncovering more rooms of tables, lamps, and most importantly fruit.
Dagon
Dagon Level 1
This is the first world that the explorer can access. A book (with an accompanying Compass item, a benefit not found in New Game+) can be found in the beginning area, which tells about this world, a temple to the water god Dagon.
Denizens that may be encountered in Dagon include Deep Ones, Bugs, Worms, Dagon Cultists, and in later levels, Flying Eyeballs and Shoggoths.
Hazards that may be encountered are spikes, harmless when walking through them, but deal 2 points of damage if running through or jumping into them.
This world contains a lot of loot which will be useful when exploring later worlds. Fountains also seem slightly more frequent than in other worlds. It is best to start out in Dagon even after all the books are unlocked because the player can easily stock up on bullets, which will be very much needed in the two other worlds.
Nyarlathotep
This is the second world of Eldritch and considered to be the most difficult of the three worlds due to how dangerous the Denizens are: Mummies that rise again when killed, Lizardmen that jump, dodge, and spit, Fire Bugs that shoot fireballs, and Lizardmen Statues that attack when not observed and are invulnerable to conventional damage (except for Dynamite).
Denizens that may be encountered in Nyarlathotep include Lizardmen, Lizardmen Statues, Fire Bugs, Mummies and Nyarlathotep Cultists.
Hazards that may be encountered are trip-wire traps that deal 1 point of damage (and may be disarmed, giving 1 bullet), unstable floors that collapse when stepped on or jumped into from beneath, and spikes.
The Tripwire Gun can be found in Nyarlathotep, as loot or in stores.
R'lyeh
The third area of the game, R'lyeh, is an sunken ruin flush with plant life.
Denizens that may be encountered in R'lyeh include the sleepy Star Spawn, Flying Polyps, R'lyeh Cultists, and harmless Deep Ones. The creatures here are resilient with many hit points, though they lack the "tricks" of Nyarlothotep's denizens, making them easier to handle.
Hazards are plenty in R'lyeh. Notable hazards include "barnacle" eyes on floors and walls that explode in poisonous gas when the explorer is near, spike walls, floor spikes, and plenty of tripwires.
The Endless Library
The final portion of the game takes place in the same library you start out in. To reach the Library stage, one must collect all three Souls from each of the three worlds, and place each Soul on the three pedestals opposite the Library Door. The door will open and the explorer can enter the second part of the Library.
Denizens that may be encountered in the Library include any found in Dagon, Nyarlathotep, and R'lyeh.
Located in each of the three levels of the Library are candles. Candles are most often located on the second floor of each level and only accessible from the top floor. Lighting all three candles before reading from the Ritual of Binding book in the final level gives the explorer the Good Ending. Failing to light all the candles leads to the Bad Ending.
There are no hazards in the Library other than menacing heights.
Shadow World
This world can be found within Dagon, Nyarlathotep, and R'lyeh by discovering a secret room containing a Dusty Book. This room is only found on one floor in each world (commonly on floor 2), and can be difficult to reach without mining its walls or thorough exploration.
Each Shadow World contains a number of Artifacts and a unique piece of equipment, none of which grant the player any special power. However these items are needed in order to achieve the Great Ending:
- Holy Symbol
- Sandals
- Consecration Kit
The order in which they are found appears to be randomized. These items are referred to in the Librarian's journal entries, which may be found in the Library.
Mountains of Madness
The expansion adds a new level in the Antarctic mountains based on Lovecraft's novel At the Mountains of Madness. The level is initially predominated by ice and snow but slowly changes over ten floors into a massive mushroom cavern as the explorer descends. Later floors are incredibly dark, making safe navigation a challenge. Several new items, denizens, and traps are introduced in this expansion:
- Penguins, Elder Things, and Mi-gos are some of the dangerous new Denizens encountered in this world.
- New weapons and tools include a Pickaxe that digs through blocks, a Hatchet that chops down wooden doors, and a Grappling Hook that shoots a climbable rope anywhere.
- Icicles scattered all over ceilings are a new hazard that will fall down upon the player as soon as they walk underneath them, doing 1 damage in the process. Equipping the Climbing Boots nullifies this hazard.
- Health is extremely rare, getting progressively rarer the farther one descends. The explorer must rely on scarce Fire Pits that restore 1 hit point when interacted with. These pits may be rekindled at the cost of 10 artifacts with the new Campfire Kit.
- There's a piece of Soapstone near the mountain entrance, but it seems to do nothing...
The Mountains are more challenging than the original three worlds due to scarcity of resources, abundance of dangerous denizens, and the length of the world itself. If you are collecting all three soul orbs, this world can be passed over and is not mandatory.
To leave this world, the explorer must descend all ten levels to retrieve a pair of plane keys, located on an altar surrounded by Cultists, then ascend all the way back to the surface level, granting the What Final Horror achievement. When the keys are taken, a black cloud hovering above the alter (the soul of the airplane's original owner?) will follow you, making strange noises. The cloud is harmless, but it may "cloud" your vision.
Completing the Mountains of Madness (returning to the plane with the keys), will end the game, restart the player with default spawning statistics (i.e. 3 HP, 0 artifacts, 0 items, etc.), and will wipe the player's progress in other worlds - in other words, completely restarting the game.
- If the player wants to experience the Mountains of Madness and return without wiping their game, the player can search for the hidden book portal, found somewhere in the bottom tenth floor. The player may have to use Dynamite or a Pickaxe to find the hidden room where the book portal is, much like the Dusty Books hidden in the Shadow World. The book should show up on the mini-map as as exit if the player has the Compass equipped.
- Regardless of whether you pick up the keys, the black cloud will not follow you back to the Library or any other world.
- If you pick up the keys before leaving, you may return to the bottom floor of the Mountains of Madness from the library at a later time. This is useful if you wish to get the R'lyeh Nice to Meet You and What Final Horror achievements during the same life.
- If you do not pick up the keys before leaving, returning to the Mountains of Madness will return you to the top floor.
- If you do not intend to return to the Mountains, you still retain all of the items and upgrades you acquired there.
Trick or Treat
A Jack-o'-Lantern can be found in the library canteen. Activating the jack-o'-lantern will send the explorer a mostly barren, dimly-lit world.
There are only two Denizens that may be encountered in this world: Jack-o'-Lantern Cultists and Shoggoths (lots of Shoggoths).
This world contains plenty of artifacts, keys, food, and ammo. There are small Jack-o'-Lanterns that can be destroyed to yield artifacts. There are piles of weapons and tools like Tripwire Guns, Grappling Hooks, Pickaxes, Dynamite, and Hatchets. A random Prayer Alter may also be present, granting magic if prayed to.
Unfortunately, guarding all this bountiful loot is a large number of Shoggoths. These ones are not only invincible but also especially fast (probably from all the sugar), often requiring the explorer to grab whatever loot is found and run for it.
Escaping this world is done by activating a giant Jack-o'-Lantern located on the bottom floor, which will take the explorer back to the Library, along with any loot they're carrying. The Jack-o'-Lantern may be re-entered in the same run just as the other worlds, allowing explorers easy access to much-needed resources.
Like the Mountains of Madness levels and the Asylum, the Trick or Treat world is completely optional if the explorer intends to collect all three souls.
- When relapsed the developer Dphrygian described Trick or Treat as "[t]his spooky level is absolutely packed with loot. Use it to gear up for adventure! Or work on that 9,999 artifacts achievement."
Asylum
The Asylum expansion is a maddening challenge level entered either via an orange-glowing Strange Book in the Library or resurrected into after dying in a failed run. Full of some of the most dangerous enemies and nastiest traps in the game, the goal is to collect as many Lost Souls as possible, portrayed as white, glowing spheres sometimes trapped in the terrain.
Upon entry a three minute timers starts counting down. Once the timer reaches zero an unthinkable entity escapes its prison and begins chasing the player in a black cloud of gurgling teeth, including through locked doors, walls, traps, and any other obstacle. Lost Souls can continue to be collected, but with far greater risk.
A new magical ability exclusive to Asylum, Soul Trap, can assist in collecting Lost Souls by destroying denizens, but at the cost of 10 Artifacts per cast.
The only way out is death. Upon return to the Library hub all items, magic, and weapons are reset as with any new game. Players may view their "Most Souls" high score in the Leaderboards located in the book to the right of the Library's Mirror.