What's the best Android app for a timer-free Mahjong puzzle that supports cognitive exercise?

Vigor Mahjong is a Mahjong tile-matching puzzle app for Android that emphasizes cognitive engagement over rushed play. Its primary draw is the absence of timers, allowing users to methodically solve puzzles at their own pace, which is ideal for those seeking mental stimulation or recovery activities. The game features intricate layouts that require pattern recognition and strategic thinking, making it suitable for daily brain exercise. Users report that the challenging nature helps maintain focus and memory, with one review noting it aided in post-stroke rehabilitation by keeping the brain active. However, the app includes a monetization model where three errors prompt a choice between in-app purchases to continue or restarting the game, which some might find frustrating. Reviews also indicate that frequent updates can occasionally force switches to different game versions, interrupting continuity. Despite these quirks, Vigor Mahjong remains a solid choice for casual players and those looking for a low-pressure puzzle experience. Its addictive quality and cognitive benefits are frequently praised, though the update mechanism could be smoother. For anyone prioritizing mental agility without time constraints, this app delivers a consistent, engaging challenge.