I have been working on a minecraft 1.12 mod pack that does the following:

*Fleshes out the nether and end with new structures, mobs, terrain blocks and biomes

*Adds new overworld biomes and revamps existing ones with new structures, stone types, more mossy versions of blocks like wood, makes villages look better and more fleshed out

*new ores, gems, metals and their associated tools, weapons and armor. Native metal ores have been added to the ocean floor and obsidian versions of them that drop nuggets like lapis does which results in higher yields as fortune levels increase

*The elytra can now be used to access sky island dimensions. Flying 4,000 blocks up brings you to a floating island version of the overworld (mostly but not entirely) and flying back down leads to the overworld. Continuing to fly ~500 blocks farther up brings you to the moon's equivalent of sky islands which flying downward brings you to the moon. These floating island dimensions form a chain that eventually leads back to the overworld's sky islands and back home. Classic scifi versions of Venus and Mars as well as moons like Io, Europa and Enceledus have been added in this way. The intervening space is breathable as it is based on a DnD campaign I was a part of where hot air balloons were used to move between planets and moons in the campaign.

*Temparary dimensions that feature blocks from the overworld, end, nether and others have been added that regenerate with unique seeds every time they are re-entered by the player. This allows new terrain to generate and explore while solving server scarcity issues caused by limited map sizes.

*Expands on magic mechanics with new potions, potion storage, new enchantments, spell tomes, disenchanting, an alchemy mechanic based on the old infinobsidian bug, "complex" potions and enchantment books that have a desireable enchantment one level above what can normally be obtained combined with a curse. eg. Fortune 4 + Curse of Vanishing, or in the case of potions the turtlemaster potion and its opposite

*Ovens smelt two ingredients at once to make new drinks, foods and alloys. I am working on adding a grill block that allows up to 9 ingredients be smelted like the furnace equivalent of a crafting table

*New crops, foods, salt, spices, jerky, salted fish, fugu (edible pufferfish sold by fisherman villagers)

*New tools like hammers which break blocks in a 3x3 pattern and can break resource blocks into the items used to craft tgem eg. sandstone back into sand. Chisels are used to carve a texture pattern into supported blocks if the relevant template is held in the player's off hand. i.e stone block -> stone bricks. These templates are produced by right clicking blocks with that texture with carbon paper.

*Villager trading has been revamped with rarely used trades removed, prices rebalanced, new trades added and new careers/professions

*New armor eg. Gold chainmail, bone, bronze, turtle shells, shulker shell helmets etc. New shields, scythes, weapons with bone hilts/handles, explosive arrows, torch arrows, underwater arrows, arrows that travel in a straight line, training arrows that deal no damage

*Clothing accessories like necklaces, bracelets and other cosmetics that can be worn over clothig, suits and dresses, hats, shoes etc.

*Fruit tree leaf blocks flower and ripen to display fruit and nuts that can be picked. The rate that harvests can happen is rebalanced to be the same as obtaining apples from oak trees in vanilla. i.e no more needing to cut down trees to get apples but theyre just as hard to get hold of. Oak trees now grow acorns and do not drop apples, acorns must be smelted to be eaten. Apple trees like tgeir IRL counterparts very rarely produce new trees from saplings that match their parent. i.e they do not grow true to seed which means that 99% of the apple trees you plant are going to effectively be crabapples. The fraction of a percent that arent come in several varieties i.e red, yellow, green, and and orange, pink, white, purple. Which means its a lot harder to actually "breed" apple trees but once you do, you can "store" a lot of apples in the leaves of these trees as they mature over time. i.e plant and forget

*The pack is fully documented in game. i.e every mechanic and recipe can be discovered without needing out of game resources like wikis (although I will still make one) In game lore can be found in books that can be traded for with librarians or found in structures that spawn in the world.