Mod idea: Into the Core.
Basically what this mod is, is a mod that explores the inner core of the minecraft world. There would be a new dimension like the nether yet not so alien, it would be a world within a world (like mystcraft cave worlds) There would be new ores, new tools/weapons, new armors and new blocks. This dimension would be ruled by ogres and dwarves with the tech focusing on lava and steam.
Multiblocks: Geothermal Reactor creation is done in a 2x3x2 (2 wide 3 tall 2 long)- Lava is put into the system in either cells or pipes and it can be automated simply enough. It can use an interface like the nuclear reactor yet it would work like a breeder reactor where it would have to run hot yet the hotter the reactor the more energy it produces (to a maximum that doesn't cause the user to take damage.) too hot and it breaks down, requiring the parts inside to need replacing. It naturally produces MJ but there is another block that would allow for the conversion to EU or other forms of energy.
Lava Boiler, works a lot like the steamboilers but with lava as it's input. Again that boiler outputs steam at the cost of lava and water. Over time it degrades slightly causing a side effect of slag like material that would need to be pipped out, this would in turn be turned into another resource that when mixed with ores will produce interesting ores that smelt to help produce more materials for different uses and decorative blocks.
In the core dimension you would find a multitude of ores and dungeons each with their own loot and bosses. I imagine a complex like the fortresses yet less like ruins. Mobs in the fortress would be teired allowing for certain wings of said fortresses to be explored, loot found, bosses killed. Each boss would have a gimmick of course along with certain sets of armor/weapons that could drop or if it's a low level boss it will drop fragments so the armor/weapons be crafted.
These armors would give set bonuses based on what they were crafted from such as one armor could come from an ogre king that would allow flight, the armor basically had to keep his fat bootay mobile yet when worn by the player has enough power to provide actual flight. It would use steam to power it up as I imagine these ogres using steam as it's primary power while dwarves are lava. Bones are now a new crafting resource allowing for the creation of bone weaponry and bone armor. It would have the same stats as chainmail and damage of iron weapons but would have lower durability and when crafted with rotten flesh give it a red coloring but enhances it giving each item +0.5 hearts per lifesteal yet each time it loses 0.5 to 1 point of armor (based on armor piece and weapons would receive a debuff, unsure of what it debuffs.).
Multiblock quarrying type device. Tunneler, tunnels out the area and replaces it with mineshafts and requires certain drill heads to allow for even faster tunneling. It would be like an arcane bore but on a larger scale, you'd craft a vertical plate of "drill engines" that once completed into the right size (think of the stuff you put down in a circle for forestry multifarms but vertical* and the larger it is the larger the hole it would bore. It could also be placed horizontally for up and down digging. It would yield all the materials it drills in an internal inventory which can be accessed by rightclicking on the main unit (which would be a 2x2 structure behind the plates) a landmark type system could be used to direct the bore along what path the player wants. Has a TON of upgradeable functions like auto smelting, lava generation (aka all the rocks it bores into turn into lava blocks, lava doesn't hurt/stop the bore, with the extreme bore upgrade it would allow for the sucking up of liquids in it's path. I have more ideas but it's late (or early) and I've not been to sleep.. I'll post more when I think of it.
