Strange Aeons

Strange Aeons is a 5-episode partial conversion for ZDoom/Ultimate Doom developed and released by Impie in the summer of 2015, then expanded in early 2016. It features 45 new maps and a large number of new weapons, powerups, and monsters. Many elements of the wad are based on the works of horror author H. P. Lovecraft, in particular "The Dream Quest of Unknown Kadath," and "The Call of Cthulhu": as a result, the megawad is very atmosphere-heavy.

Releases
Strange Aeons was planned as a four-episode megawad for ZDoom, with the main story concluding in Episode 3. On July 22, 2015 it was released as a 3-episode beta. Episode 4 was added a month or so later.

In 2016 Impie added a 5th and final episode, bringing the total level count to 45.

Story
The player controls the nameless Traveler, a Miskatonic University researcher who has recently lost his son David in a tragic accident. To cope with his loss, the Traveler has begun an obsessive translation of the Kadath Tablets, which appear to have a strong connection to the treacherous Dreamlands. After seeing visions of his son alive and well in a utopian world, the Traveler embarks on a dream quest, traveling across the cosmos through his dreams in the hope of reuniting with his son.

The fifth episode, Out of the Aeons, is a spinoff story. The Traveler returns to the Dreamlands to save his nephew Daniel and prevent him from inadvertently awakening Cthulhu.

Episodes
Each of the three episodes takes place in a unique world that is drastically different from the others. The Shattered City has a "broken world" motif, with buildings and rock formations drifting through empty space. The Stagnant Fortress features rusted, dilapidated buildings of the future filled with toxic sludge, crushers, and conveyor belts. The Land That Time Forgot is a prehistoric world with a vaguely Egyptian/Aztec theme. Occasionally these worlds bleed into one-another, such as during the boss battle at the end of World 1, where the Traveler is suddenly transported to World 3. The bonus episode, Plateau of Leng, takes place in an icy, mountainous wasteland populated by gunmen and giant spiders, and serves as the original story's epilogue.

In the fifth episode, the Traveler explores the Underworld, a subterranean haven of undead monstrosities, notable for pillars of light piercing through the ceiling from the surface world above. The final two maps take place in Cthulhu's city of R'lyeh, where mossy rocks and soapstone spires cover the landscape.

Weapons and Powerups
Strange Aeons modifies a couple of the original Doom weapons, and replaces most of the weapon sounds.
 * In older versions, the pistol has new graphics and sounds, but behaves the same. It was replaced by the Scepter of Souls in version 5.0.
 * The most notable change is the AK47, which replaces the chaingun and fires slightly faster.
 * The plasma gun is replaced by the Yithian Lightning Gun, a powerful weapon which can only be found on the secret levels.
 * The Scepter of Souls is added to the arsenal, behaving like a mid-range chainsaw that requires no ammo.
 * Version 5.3 added the Impaler crossbow to the arsenal, which fires flaming bolts that pierce through lines of enemies. Like the Scepter, it requires no ammo, but it is weak and fires slowly.

In addition, three new powerup artifacts are present.
 * Ammo Sphere gives the Traveler unlimited ammo for a short time.
 * Rage Sphere doubles the firing rate of all weapons.
 * Mutant Sphere turns the Traveler into a towering hulk that smashes monsters with his fists, but cannot pick up items.

Levels
Episode 1: The Shattered City Episode 2: The Stagnant Fortress Episode 3: The Land That Time Forgot
 * E1M1: The Traveler
 * E1M2: Resident Evil
 * E1M3: Shooting Range
 * E1M4: Cowboys and Indians
 * E1M5: Highly Terminal
 * E1M6: Island Hopping
 * E1M7: Halls of Madness
 * E1M8: Deathedral
 * E1M9: Haunted Hospital
 * E2M1: Beast Depot
 * E2M2: Power Station
 * E2M3: Ore Devourer
 * E2M4: The Marrow Engine
 * E2M5: Juggernaut
 * E2M6: Eldritch Research
 * E2M7: Underworld Gate
 * E2M8: Siege of Pnath
 * E2M9: Petting Zoo
 * E3M1: Altar of Blood
 * E3M2: Monster Manor
 * E3M3: City of Lost Souls
 * E3M4: The Gondola Grotto
 * E3M5: Lions Den
 * E3M6: The Vampire Trough
 * E3M7: Proving Grounds
 * E3M8: Flytrap
 * E3M9: Tomb of the Dark Pharaoh

Episode 4: The Plateau of Leng Episode 5: Out of the Aeons
 * E4M1: Cold and Stranded
 * E4M2: Hell Frozen Over
 * E4M3: Twilight Meat Train
 * E4M4: The Biospherians
 * E4M5: The Salt Mines
 * E4M6: Alcatraz
 * E4M7: Devil Canyon
 * E4M8: The Crawling Chaos
 * E4M9: Maniac Mansion
 * E5M1: Rigorous Mortis
 * E5M2: Drought Station Acheron
 * E5M3: The Vaults of Zin
 * E5M4: Valley of Death
 * E5M5: Man Flesh Processing
 * E5M6: Cthonian Planet
 * E5M7: The House of Dagon
 * E5M8: R'lyeh Rising
 * E5M9: Mysterious Island

Assets
The entire bestiary has been replaced with modified creatures from Realm 667, many modified to resemble creatures from Lovecraft's Cthulhu and Dream Cycle mythoses. Custom graphics were made for the Episode 2 and 3 end bosses. The vast majority of the level textures are from Chasm: The Rift, as is the majority of the soundtrack and many of the sound effects. The main theme is from Amiga shooter "Death Mask".

Lovecraft mythos
In addition to references to  and the inclusion of the Plateau of Leng and R'lyeh, the mod has a number of other Lovecraftian elements.


 * The hooded shotgunners are referred to as the Men from Leng, and are among the most common enemies. They move and shoot twice as fast as a normal Doom shotgunner. Leng Chieftains are tougher, more powerful versions with super shotguns.
 * Modified dianogas called Spawn of Glaaki attack the player in watery areas. The dianoga has a striking resemblance to Ramsey Campbell's one-eyed, slug-like deity.
 * The player frequently makes use of ghoul allies in Episode 2, which eventually leads to the Underworld and a massive final battle on the Vale of Pnath. The ghouls help the player again in Episode 5, where he visits the Vaults of Zin.
 * The boss of Episode 2 is the massive Dhole, many of which dwell in the Vale of Pnath. The preceding battle between ghouls and demons awakens several of the beasts and draws them to the player.
 * Spider god Atlach-Nacha serves as the final boss of Episode 3, and the primary antagonist of the main story arc, given its connection with the Dreamlands. This is why its worshipers, the Leng Spiders, are commonly seen throughout the mod as enemies, symbols, and otherwise.
 * Nyarlathotep appears more than once as a "bonus" boss, which must be avoided rather than fought.
 * The Star Vampire is infrequently encountered throughout Episodes 3, 4, and 5. It is essentially a flying Nightmare whose laughter gives away its presence.
 * Flesh Spawn are referred to as children of the vile deity Abhoth.
 * The mod's ultimate weapon is the Yithian Lightning Gun, which is powerful enough to tip the balance of the game considerably. It is hidden on each of the four secret levels.
 * A difficult-to-find secret area in Episode 4 references .
 * The Dimensional Shambler appears in Episode 5 as an infrequent enemy, teleporting toward the player at frightening speed. It is a reference to one of the original Doom exit prompts, warning that a Dimensional Shambler lurks at the DOS prompt.
 * Episode 5's plot is reminiscent of the first chapter of The Call of Cthulhu, regarding an artist tormented by dream-visions courtesy of the squid-like Ancient One. In E5M8, the player faces a group of gigantic Star Spawn, which greatly resemble Cthulhu and can revive each other.

Other notes

 * Impie based the project on the first "Doom clone" he came up with following his first exposure to Doom in 1995. Several maps are based on his original map sketches from that year: E2M1, E3M4, E3M8, and the dimensional travel sequence at the beginning of each episode.
 * The mod comes with a pdf "instruction manual" which describes the story, new additions, and asset authors.
 * The purple tentacles in E4M9 are a reference to Maniac Mansion and its sequel, Day of the Tentacle. The map itself is a remake of the first floor, asylum, and astral plane maps from another Lovecraft-inspired computer game, The Legacy: Realms of Terror.
 * E5M9 is a giant Myst reference, reproducing the original Myst Island in the Doom engine. Players who know how to solve the puzzles of Myst Island will already have some idea how to acquire all the secret goodies.