What is known about inferno:Items and Runes specific to that difficulty, with specific looks/graphics.
- Highest level of difficulty in the game.
- Minimum Enemy lvl of 61 across the entire difficulty.
- More aggressive monster behavior with modified AI, and possibly exclusive boss modifiers (or a higher chance of rolling specific [nasty] modifiers) for Inferno.
In addition to that summary, this is official Blizzard word on the matter as well, from an interview with popular gaming site Kotaku:
Monsters will see an increase in health, damage, damage resistances and aggression in Inferno. They’ll also have access to a larger suite of powers in Inferno, making minions and boss monsters even tougher. Expect a tougher game across the board, with broader than ever challenges even for the most skilled demon hunters.
“The idea was that we wanted a difficulty mode where the entire game was viable,†Wilson says. “So you don’t have to pick and choose key areas [to replay].†Diablo III’s Inferno difficulty, he says, will be “very difficult, very challenging,†presenting a “flattened†difficulty experience that Blizzard hopes will provide a more balanced, but more challenging end game for Diablo diehards.
That “flattened†difficulty will mean, Blizzard hopes, that players revisit the entire world of Diablo III seeking bigger and bolder challenges, not just go on “Mephisto runs†or fight a specific breed of minion in search of experience points and sweet loot drops.