
TouchArcade: Highline Games have released W.E.L.D.E.R. [$1.99] which stands for 'Word Examination Laboratory for Dynamic Extraction and Reassessment", The amusing game trailer (below) suggests that words are at risk of becoming extinct, but that's not really part of the gameplay. It's just more interesting than saying: "Move letters around to form words", which might sound dull and done-to-death; but this intriguing word game is neither of those things, it's unique and will activate your brain.

AR: Word games of any kind are challenging. W.E.L.D.E.R. is not like most word games out there. It’s almost a combination of a Scrabble and a puzzle game like Bejeweled. In this case, it’s a matter of spelling words vs. matching colors.

MacWorld: So, you say you enjoyed those word-search puzzles flung at you in third grade—the ones where you’d try to find the words hidden in a large grid of letters. And you appreciate the satisfying effect that occurs when you clear a Tetris row. And you relish games that slowly but oh-so-surely become more challenging over time. And you have a thing for steam punk interfaces. Then Ayopa Games’ $4 W.E.L.D.E.R. is for you.

Pocket Gamer: iOS isn't exactly hurting for word games. There's the asynchronous Words With Friends, the enchanting SpellTower, and the spineless Bookworm. There's Wurdle and Scrabble and Boggle and Quarrel Deluxe. More than 300 App Store results for "anagram" and 400 for "hangman".
In fact, if you're a lexicon fiend - the sort of vocabulary collector whose favourite tome is the dictionary and whose favourite follow on Twitter is Miriam Webster's Word of the Day - you won't struggle to find something to suit your taste.