Well, they have a dedicated NPC that lets you enable various “Iron Man” modes.
Standard Iron Man:
-You can’t trade with other players or pick up items from other player’s kills
Hardcore Iron Man:
-Same as previous but you only have one life.
Ultimate Iron Man:
-Same rules as the first and second rank but you also can’t use banks except to un-note items
With each rank you get a unique armour set and there’s a dedicated scoreboard.
They could easily add a new alternative playstyle to Classic, but yanno, no changes.