Brunel is a modpack bringing a world of steam, steel, railways, and massive machinery to Minecraft 1.12.2! Featuring the pairing of Immersive Engineering and Railcraft, it aims to bring the steam age to life within Minecraft. Of course, in order to make building an advanced rail system worthwhile, all the resources in the game have been scattered so that only a few of each may be found in any given biome, and even the biomes themselves have been arranged to put colder climates to the north, and warmer climates to the south. Finally, to ensure you really do need the railroad, all stack sizes have been dramatically reduced so you're really want those rails!
Along with Immersive Engineering comes a large collection of companion mods for oil drilling (Immersive Petroleum), steam-powered electric generators (Immersive Tech), long distance wires (Alternating Flux), and a huge collection of decorative items from steel fences to girders and I-beams (Engineer's Decor, Engineers's Doors). Plus, many, mnay other mods adding: custom doors, roofs, bridges, and windows (Macaw's mods); architectural elements (ArchitectureCraft, Cathedral); household items (BiblioCraft); and lots more. If you can't find something, you can even make it yourself (Chisel, Chisels & Bits).
But, Brunel isn't only all technology. Real industry starts with the products of the land. So, you'll find many species of cows, pigs, etc. waiting to be domesticated (Animania) in nearly every corner of the land along with many wild animals (BetterAnimalsPlus). While there are no zombies, skeletons, or creepers to contend with, you may find the bears, boars, and feral wolves are more than enough to warrant making a revolver for self-protection. In addition to the fauna, a tremendous diversity of trees and wild plants abound (Forestry): including many species yet to be discovered (Agricraft). Gone are the blocky, gravity-defying trees of vanilla Minecraft, and in their places are actual living, growing trees which must be seen to be believed (Dyanmic Trees).
Even the land itself will take your breath away with smooth plains rippling into rolling hills and rising up to majestic mountains (Realistic Terrain Generation). Unlike vanilla Minecraft, biomes subtly transition from arctic conditions in the far north through all the various bands of temperature to scorching deserts in the south. At no point does one encounter jarring transitions of any sort. Just beautiful countryside to enjoy as you ride the rails!
Brunel has a lot of mods, and many of which have been altered to work better together. Plus, it has a lot of custom world generation, so you won't be able to find things in their usual places. Finally, there have been more than a few little tweaks to both make things harder, easier, and just more integrated. The wiki associated with this repo will describe what you need to know to navigate the new terrain. Just click on the word "Wiki" above the big green button.