In the world of Minecraft you have 3 dimensions, the Overworld, the Nether and the End. The Overworld is the place where you live, the Nether is the hellish place where you get materials used later, and the End is where you fight the Ender Dragon. One thing in particular that isn't defined in Minecraft is a world of the dead (you could essentially call the Nether a world of the dead, as that world contains a large amount of dead things among the other burning entities), the Underworld, the Abyss, and that's where this mod kicks in, by opening the gates of a world composed of death, a place where the absence of life has let a darkness take over what might've been a peaceful place. 

What my mod gives you is the opportunity to go beyond death (while still being alive), by crossing between 3 dimensions placed on top of each other like layers (where each one takes you further down into the darkness). These dimensions are the Abyssal Wasteland, the Dreadlands and Omothol. The Abyssal Wasteland contains more "regular" dead beings (skeletons, zombies, ghouls, spectral dragons, cudgel-wielding skeleton goliaths), and a boss who is the reanimated remains of a long dead dragon, brought back to life through the use of a altar. The Dreadlands contains mutated demonic abominations (and a large three-headed behemoth, guarding the component required to advance to the last dimension). Omothol is the final dimension, and also the one that is currently incomplete. Inside Omothol you can face the ancestral breed of the ghouls found in the Abyssal Wasteland, not to mention the evil demon who guards the Abyss (who currently also is incomplete). From one perspective, you could say Omothol is the most friendly dimension among the three, with it's inhabitants of nameless beings willing to trade goods with other life forms capable of making it this far (but if you were to, say, hit one, you will suffer the wrath of them).

Now, enough about the dimensions added by the mod. In the Overworld you will find 6 new biomes, the Darklands (could count as a more evil version of the regular biomes, with a plains version, a forest version, a more elevated version, a mountain version and the regular, which is a mix between a forest and the plains) with it's purple terrain and nightly undead population (among the regular Overworld entities that appear during night). Then there's the Coralium Infested Swamp, which is a Swamp converted by the influences of Coralium (a element commonly found in the Abyssal Wasteland). In this biome you can entities made out of antimatter (which can be found in liquid form here, very lethal), who explodes if they collide with their normal counterparts, thus following the antimatter principle.

In mob ways, this mod offers a large quantity of undead mobs, with the exceptions of the living shadows and the anti-mobs. Among these are the Depths Ghouls, found in Darklands biomes, any Swampland or Ocean, and within the Abyssal Wasteland. Then there's the Abyssal Zombie, which is a new breed of Zombies made through interactions with the Coralium Plague. Abyssal Zombies are hostile towards normal Zombies (as they kill them to spread the plague even further), and can be found within the same biomes as the Depths Ghouls (apart from these also spawning in the End). There are a lot more entities, and quite frankly it would take a lot of text to cover all of them here. A bit further down I will explain a way to easier obtain this information.

In block ways, you can find 7 new stone types, among them Darkstone (found in the Darklands), Abyssal Stone (found in the Abyssal Wasteland), Abyssalnite Stone and Dreadstone (found in the Dreadlands), Omothol Stone (found in Omothol) and Coralium Stone (created by pouring Liquid Antimatter on Liquid Coralium, found in the Abyssal Wasteland). There are also 2 new types of wood, called the Darklands Oak and the Dreadlands Tree, found in their respective locations. There is also a lot of new ores added, among them the Abyssalnite Ore (found in the Darklands and inside the Dreadlands), Coralium (found inside ocean biomes, swamps and the Abyssal Wasteland in many different forms), and Nitre (found in any Overworld biome), which doesn't have that much of a use yet. There are also "abyssal" versions of regular ores found in the Abyssal Wasteland (most regular Overworld ores except redstone and coal, Tin, Copper and Nitre).

In item ways, you can find anything from tools and armor to flesh made from antimatter. There are Armor sets and Tools for each new material added (Abyssalnite, Refined Coralium, Dreadium, Ethaxium), some special sets for each material (apart form Ethaxium) which requires additional materials. You can find a range of new foods, among them Fried Eggs, Food on A Plate (you can create Iron Plates and put regular food on them to amplify it), MRE (meal ready to eat), various types of flesh dropped from the mobs (which is very unhealthy).

Among the items is also the Necronomicon, which is the information book for this mod. A Necronomicon can be crafted by surrounding a Book with Rotten Flesh (but place a Iron Ingot in the bottom and top right slot). In each dimension, you can empower the Necronomicon by surrounding it with a piece of flesh from a mob found there, which unlocks new knowledge in the book. The Necronomicon is currently under development, but it has information that covers the mod progression and information on materials found in each dimension. Later on you will be able to cast spells with it, and perform rituals in order to obtain certain things (or summon beings from beyond).
 

Mod includes:

• 5 new types of stone, called "Darkstone" (It's 20% stronger than regular stone), "Abyssal Stone" (generates within The Abyssal Wasteland, "Dreadstone", "Abyssalnite Stone" (generates along with Dreadstone in The Dreadlands), and "Coralium Stone" (created from pouring Liquid Antimatter on Liquid Coralium). All of the stones have brick equivalents.
• New tools, 5 types so far, Darkstone, Abyssalnite, Coralium infused abyssalnite (2x the stats of abyssalnite with special abilities), Refined Coralium and Dreadium.
• 6 new type of armor, Abyssalnite, Coralium Infused Abyssalnite, Dreaded Abyssalnite, Refined Coralium, Plated Coralium, Depths, Dreadium and Dreadium Samurai.
• 7 new overworld biomes, called "Darklands", "Darklands Plains", "Darklands Forest", "Darklands Highland", "Darklands Mountain", "Coralium Infested Swamp" and "Coralium Infested Ocean".
• New mobs, so far 16, the "Depths Ghoul", the "Abyssal Zombie", the "Evil Pig" (a hostile pig that looks like a normal one), the "Spectral Dragon", the "Skeleton Goliath", the "Shadow Creature", the "Shadow Monster", the "Shadow Beast", the "Demon Pig", the "Abyssalnite Golem", the "Dreaded Abyssalnite Golem", the "Dreadguard", the "Dread Spawn", the "Dreadling", the "Spawn of Cha'garoth" and the "Fist of Cha'garoth".
• A new trader mob, called the "Remnant". They spawn in the 3rd dimemsion, but can also be created by pouring Liquid Antimatter on a Villager.
• 11 "Anti-mobs", including the "Abyssal Anti-Zombie", the "Anti-Bat", the "Anti-Chicken", the "Anti-Cow", the "Anti-Creeper", the "Anti-Ghoul", the "Anti-Pig", the "Anti-Player", the "Anti-Skeleton", the "Anti-Spider" and the "Anti-Zombie". All Anti-mobs explode if the collide with their normal counterpart (except the Anti-player).
• 4 boss mobs (known as "Asorah, The Fallen", "Cha'garoth, The Dreadbeast", "Sacthoth, Harbringer of Doom" and "J'zahar, Gatekeeper of The Abyss"). J'zahar currently isn't complete, while the others have been fully implemented (but Asorah could use a few small improvements).
• A new dimension, The Abyssal Wasteland, a dimension filled with undead monsters, where you can find abandoned strongholds with the use of "Powerstone Trackers". There's a boss here called "Asorah, The Fallen" who can be summoned through an altar made from various materials.
• A second dimension, called The Dreadlands, a desolate red dimension filled with Abyssalnite Golems and Dreaded Abyssalnite Golems, who constatly fight each other. There's also numerous Dread-plagued monsters found here, along with the Dreadguard, who guards the fortress of Cha'garoth in the Dreadlands Mountains.
• A third dimension, called "Omothol", a realm consisting of structures built on floating islands, where you'll face "J'zahar, Gatekeeper of The Abyss". This dimension is currently a work in progress, so currently only the islands generate, without buildings nor mobs.
• 14 new ores, known as Abyssalnite, Coralium, Nitre, Abyssal Coralium, Pearlescent Coralium, Liquified Coralium, Abyssal Iron, Abyssal Gold, Abyssal Diamond, Abyssal Tin, Abyssal Copper, Abyssal Nitre, Dreaded Abyssalnite And Dreadlands Abyssalnite. The first 3 are found in the overworld (Nitre appears anywhere, Abyssalnite appears in the Darklands biomes and Coralium appears in Coralium Infested Swamps and ocean biomes), the 9 after are found in The Abyssal Wasteland (first dimension), and the final 2 are found in The Dreadlands (the second dimension).
• The "Oblivion Deathbomb", a heavily engineered explosive that can destroy anything except bedrock (and which spawn "Sacthoth, The Habringer of Doom"). The ODB (shortened version of the name) has a core which can also be used as a fairly strong explosive (stronger than tnt).
• 3 new Machines (called the "Crystallizer", the "Transmutator" and the "Engraver"). The Crystallizer can convert elements into crystal, while the Transmutator can transmutate various elements (and also convert crystals back into base components). The Engraver can be used to engrave blank coins (crafted by placing ingots in a plus sign formation, with a piece of flint in the middle).
• 2 new trees (called the "Darklands Oak", and "Dreadlands Tree"). The Darklands Oak is found in various Darklands biomes, while the Dreadlands Tree is found within the Dreadlands Forest biome, located in The Dreadlands.
• 4 new enchantments, "Coralium", "Dread", "Light Pierce" and "Iron Wall". The Coralium and Dread enchantments applies Coralium/Dread plagues on hit. The Light Pierce enchantment functions like Smite/Arthropods/Sharpness, but against Shadow Mobs. The Iron Wall enchantment negates any knockback delivered from attacks.

Highlands aims to be a comprehensive improvement of Minecraft biomes, trees, and terrain. If you've ever felt bored exploring the world of Minecraft, this is your mod. In 1.8, Highlands is going into uncharted territory, where no biome mod has gone before. It's been designed from the ground up, and features from the old 1.6.4 Highlands will be added in as they are updated. Highlands also gives you an incentive to explore into uncharted territory, whether to search for the perfect mountain to build a base on, to complete your botanical garden, or to search for more lucrative mining opportunities.

Features:

18 new biomes!
8 trees, all with their own wood, leaves and planks!
6 small plants!
Custom world type and mountain generation!
Fully compatible with customized world settings!
Settings to disable biomes you don't want!
Biome rarity fix!
Ore generation changes per biome!
Forest generation based on height!
Improvements to vanilla biomes!

Ever felt like the oceans in Minecraft are a bit boring? Don't you wish they were a bit more beautiful and/or mysterious? Well so did I, and after working for few weeks, I now proudly present to you the Aquatic Abyss!

In this mod, Minecraft's boring oceans are populated with tons of new mythical and real creatures, along with new world generation!

There is it finally, the new version of Oceancraft for minecraft 1.7.10, oceancraft is a mod, which makes the ocean biome in minecraft much better, it adds life in the oceans and around the oceans, there are 11 brand new mobs for the ocean and around the ocean.

but thats not everything, there also are lots of new blocks and new items, and also very beautiful world generations, like pillar huts with beach villagers in there, or oyster at the bottem of the ocean and seaweed, and much more.

What does it do?

New Dawn adds a new world type "New Dawn" that uses a custom terrain engine for the overworld map, where biomes are no longer distributed randomly, but are placed according to the area's temperature and humidity. This results in a much more realistic and smoother world than what you see in vanilla Minecraft. 

When creating a new world, make sure to go to advanced options and select level type "New Dawn". 

If you run this on a server, make sure the server.properties file contains the setting "level-type=New Dawn".

New Dawn pre-generates a humidity and temperature noise map (as well as some others) then decides for biomes based on the combined noise fields. This means you will for example never find deserts next to snow, because the temperature drops gradually. You will find Savannah or Jungle near a desert and following the dropping temperature through temperate plains you will eventually find snow covered areas or frozen oceans.

While trying to keep this realistic, I still try to keep the game playable however. Therefore those temperature/humidity maps are - compared to the real world - unrealistically small. So a desert might be only 2000 blocks away from an arctic see, but then you probably do not want to travel 2,000,000 blocks just to have a realistic world. 

More realistic generations, biomes are not a thing anymore (instead an area is characterized by temperature, humidity, and altitude, allowing for nearly infinite amount of "biomes").

Trees no longer are boringly structured, they are generated realistically, using a geometric principle real trees are using - allowing for dynamic shapes that vary based on the area they grow in.

Caves are much more interesting, less "tacked on" feeling. The generation of the world will also not be flat, there will be less oceans and in general it will be more like real life in the way things look (with all of the beautiful structures nature creates).

I started this mod on a simple idea that came to me when playing on a modded server, I wanted to create a mod like the nether. So I started modding this mod : the "Eternal Frost". This mod is a "dimension" mod, so it adds the ability to teleport to another dimension which is have called the "Eternal Frost" (Old name is the "Freezer"). In order to teleport there, nothing more simple, just craft "The flint and diamond" and create a normal nether portal but filled with ice obsidian instead of obsidian. Then use the flint and diamond to make the portal appear. In the Eternal Frost, you'll end up either underground or overworld in a beautiful world made ​​of various blocks going from deeply frozen stone to freezing water that'll hurt you on touch.

What Does the mod actually add:

83 Blocks (Without the metadata) : Every blocks is different and some are totally awesome !
127 Items : From simple stick to epic dungeon drops.
5 Complete Toolsets : Arctite Tools, Snowbark Tools ,Crystal Tools, Frozen Cobblestone Tools and Coldsteel Tools
19 new mobs (Fury boar, Glace, Ice Cube, Ice Pig Zombie, Cold Creeper, Frostbite Spider, Scarab, Snow owl, Goat, Horned Goat, Woolly Mammoth, Yeti, 2 bosses (And one boss minion), Saber Tiger, Arctic Fox, Polar Bear, Villagers)
1 Dimension : The Eternal Frost, with a totally epic generation who goes up to layer 256 !
2 Furnaces : Ice Oven which can freeze things into Eternal Frost items, Frozen furnace which can reheat them.
Structures : Villages, 2 Epic Dungeons to conquer (With two mores to come soon), the caverns have been reworked to fit the mod.
Many generations (Icicles, Trees, Lakes, Rivers, ...)
Epic items and armors to obtain in dungeon, totally unique.
An hypothermia mechanics : Don't let your hearth grow cold.
25 new sounds and 4 new musics.
14 achievements : To make this mod challenging.
8 Biomes, on surface for an epic generation : You'll have to discover them yourself.
Some secrets to discover.
Lot of things aren't in this list ... (A humonguous list trust me, pretty impossible to write every add-ons)

Read this before playing:

Hypothermia :
As you may know, there is a new mechanic : The Hypothermia. How does it work ? Simply as the hunger one, but to replenish it STAND NEAR HEAT SOURCE (Like Fire, Torch, Heatstone).

Biomes :
In order to find the biomes on the screenshots, you just have to climb up to layer 180+. There is a surface ! And that's an important part of the mod.

Other mechanics :
You can find mobs more often depending on your height : More you dig down, more you'll encounter aggressive mobs. Surface is for passive mobs.

Dungeons :
In order to be able to challenge a dungeon, you'll have to find a "dungeon block". They're not spawning naturally for lagging reason.

It's lagging !
The first time you'll enter the world (If you create a server), it'll lag for 1 or 2 minutes : That's totally normal and it won't last long ! I won't change Minecraft base class to change the entire generation logic of Minecraft and therefore the generation part is laggy.

What block, what tool?
What block (Just the stuff you use your Pick for) is succesfully mineable with what tool ? I made it here.

Every Pickaxe :
Frozen cobble
Frozen stone
Deepfrozen ice
Ice oven/Deepfreezer

At least Frozen cobble
Arctite ore
Frozen brick things
Frozen button
Frostbite spider spawner and all spawners yet to come in the Eternal frost

At least Arctite
Bluestone ore
Crystal ore
Block of Crystal
Bluestone lamp

At least Crystal
(None)

If you mine these blocks with another tool, it won't succefully drop. (But if you use Crystal tool on any blocks that need at least a frozen cobble pickaxe it'll work).

How?
When it's snowing, any snow blocks that have a view of the sky will randomly grow one layer higher every once in a while. Also, when snow blocks melt, they don't melt all at once, but instead one layer at a time. Snow will never pile up more than one block.

Why?
Because it's more realistic, and it looks pretty too.

Start by creating a new world. Then click "More World Options". Then click "World Type" until you see "Biomes O Plenty".