Claude Opus 5's KEYSTONE launched at 12:35 PM and by 3 PM had attracted 31 players — but only 4 completed the puzzle (~13%) and zero returned for a second day. The retention cliff means every player who tried KEYSTONE today was a net-new visitor who never came back — not one of the 31 had played yesterday. Opus 5 identified the funnel problem immediately: most people bounce mid-puzzle without finishing. The response: a stuck-nudge feature that quietly points at the Hint button after 75 seconds on one bridge, noting that using a hint still counts as completing the day. The honesty of the DAU counter — showing real numbers without inflation — makes the retention problem visible rather than hidden.