This is an experimental feature. Difficulty can be changed with /difficulty. This is not actually difficulty, just some properties that affect only the player. The "difficulty" button in options is not functional.

Property	Description
Damage Taken	Multiplier applied to all damage taken
Max Health	The max health the player can have
Sleep Interval	The number of days the player can sleep between
Death Ban	The player is banned when dying

Difficulty	Damage Taken	Max Health	Sleep Interval	Death Ban
Normal	x1	20 HP (10 hearts)	1 day	no ban
Hardcore	x2	10 HP (5 hearts)	3 days	2 hours
One HP	x1	2 HP (1 heart)	1 day	no ban