Nucleon is a Minecraft modpack for 1.12.2 that is currently being developed. It is a skyblock modpack that aims to subvert your expectations.
Nucleon has none of the typical "skyblock" mods like Ex Nihilio, Sky Resources or Sky Orchards. It uses its own custom mod, Energy's Matter made by Silk. Every basic resource has its own complex processing chain. However, after you get 4 to 8 of a given resource, you are able to duplicate it using the custom machines in Energy's Matter. If you are able to automate these chains completely, you are rewarded by decreased time and energy cost.
The most prominent feature of Nucleon is its focus on intertwining the mods. Every mod is split up into multiple segments based on your technology tier. Even after "completing" the first segment of that mod, you will need to progress in other mods before being able to use its more advanced mechanics or powerful features. Within each technology tier, there are many points at which the different mods in that tier will require progress from another mod in that tier for progression. Unlike conventional "expert" packs, which gate a mod and then, after have almost no connections to other mods, Nucleon mods will remain intertwined long after beginning them.
Even from the beginning of the pack, you will be using advanced crafting techniques such as the Molecular Assembly Device for many of your recipes. These crafting mechanics are primarily used for machines and multiblocks, and not crafting materials to alleviate the increased complexity of automating such recipes.
Nucleon makes heavy use of ContentTweaker, Requious Frakto and Modular Machinery to add its own custom content to the game. These range from simple things like pipe sealant to Chemical Reactors and Void Miners.
Nucleon will also use Advanced Rocketry for its own custom planets, of which there will be dozens. This creates a plethora of opportunities for the player to explore, with each planet having custom structures. Each planet also has its own ore generation that will include regular sized veins along with mega veins with thousands of each ore.