1. First Person Multiplayer Perspective
2. Piece by Piece castle construction system(including a spike wall to hang the corpses of your vanquished foes on)
3. In depth crafting system
4. Fast paced aim required melee/ranged combat system
5. Stamina/strength/hp stat system to make in combat decisions matter. When stamina empties strength substitutes, lowering strength results in less damage dealt. If strength empties hp substitutes meaning you can actually kill yourself from exertion. The gameplay depth this will provide to combat will be awesome.
6. Catapults to blast open enemy castles and pillage their chests
7. In depth farming system tied into livestock(captured cows will produce manure needed for growing crops and as a fuel source for creating top tier equipment.
8 Farm plots and animal pens are placed the same as the castle system, design your castle how you want. Protect your crops and animals with a layer of stone walls to protect them while your offline.