The goal of the pack is to the complete the "Bragging Rights" questline - Crafting one of every available creative item.
Quests! There are currently over 650 quests, that guide you through the progression. You can see most of them in the Images tab above.
Semi-linear gated progression - At every Technology and Magic tier you'll have the choice between several different mods.
Tougher mobs - Dragons, Cyclops, Zombies with Quantum Armor and many more unique threats.
Tons and tons of custom recipes.
The progression will lead you to Space, where you'll have the opportunity to explore custom worlds.