The phrase "unrelenting challenge" means a difficult situation or problem that doesn't stop or get easier. It implies that the challenge keeps coming and requires constant effort and determination to overcome. Full definition
Dark Souls II will continue a legacy of presenting its passionate fans with the kind of unrelenting challenges that have become a hallmark of the series, while presenting devilish new obstacles for players to overcome. (totallygn.com)
Dark Souls II will continue a legacy of goading its passionate fan base with unrelenting challenge and suffering that are considered a hallmark of the series; while presenting new devilishly devised obstacles for players to overcome. (totallygn.com)
Players will travel across a wide variety of locations in an interconnected world of unrelenting challenge and deep RPG gameplay as they search for a way to survive the coming apocalypse.» (xboxenthusiast.com)