What's a good iOS game for unwinding that also subtly exercises cognitive skills, like vocabulary?

I've been exploring 'Serene Word Puzzle' recently, and I find its approach quite pedagogically sound. The game mechanics are simple – connecting letters to form words – but the increasing difficulty provides a gentle cognitive workout. It's an interesting implementation of adaptive difficulty, ensuring the game remains engaging without becoming frustrating. I appreciate the clean, uncluttered interface; it minimizes distractions, allowing for focused relaxation. This could be helpful for academics who need a mental break but don't want to completely disengage their minds. The cross-platform compatibility is a plus, allowing play on both my iPhone and iPad. It's a novel approach to an old problem: providing accessible cognitive stimulation in a calming format.