Improved Stealth

If you didn't know, Minecraft has a stealth system (that's what crouching/sneaking does apparently). I think stealth could be greatly expanded on with new items, enchantments, and game mechanics. 

In its current state, stealth feels slow and unrewarding. To make stealth more rewarding, attacking an enemy that is unaware of the player should deal bonus damage, or stun/slow the enemy. A new alert mechanic could make stealth have higher stakes. If an enemy spots a player sneaking up on them, all nearby enemies would be alerted of the player's location (like a zombie pigman.) Through enchanting, a player could make a weapon deal more stealth damage or make boots quieter, so players can get closer to enemies (this would also pair well with the warden.) The wardens sound mechanics could also be applied to mobs. Enemies could be moved by throwing snowballs or eggs in another direction, making it possible to take on mobs one at a time. A new arrow or throwable could stun an enemy on hit, so it wouldn't alert other enemies.