Simple concept. On character creation you can choose whether or not it's an ironman character. A window pops up detailing the mode. Increased grind (~2 months long). When you reach a certain point in character progression (not sure how this would be determined), you are rewarded with a unique title and cosmetics that only other ironman players will have. No trading other players. No picking up dropped items. No looting player graves. No clan bank access. For monster graves if an ironman player opens it first, nobody else can loot it. But if a non-ironman player opens it first, the ironman player(s) can't loot it. Basically, no interaction with other players other than being in a clan/party. Can be disabled at any time but you cannot return back to this mode afterwards. However when you finish ironman mode, you can disable it and keep the rewards. Other players can identify ironman characters with some small text underneath their name similar to how the Villain/Saint titles were shown when they were first introduced. This forces a completely self sustaining grind for the people who enjoy that kind of thing (oddly enough I'm craving a grind right now in ROA) and it could draw in the type of people who enjoy the ironman mode in Runescape.