Despite the name, Path of Exile’s upcoming Ruthless mode will in fact allow you to have a character named Ruth, or Ruth-Anne, or Ruthie. Any variant of Ruth you might like. What it will be is ruthless in its difficulty, and the initial outline has led to some confusion regarding exactly how ruthless it’s going to be, which has prompted the developers to answer some questions. For example, if a given feature in Ruthless mode is impossible due to the lack of teleport abilities? That attack should be toned down in Ruthless and normal gameplay modes.
The FAQ also takes pains to point out that this is not replacing the 3.20 expansion in any way, nor will there be normal challenges just because of how they might become unintentionally limiting with the Ruthless mode. Players can also not look forward to a Ruthless-specific item filter, although given the paucity of items dropped in that mode this may not be terribly relevant. If the mode’s initial announcement has you asking some questions, odds are good those questions have been answered here.