Technology and innovation is moving at a dizzying pace, and perhaps no more so than in the world of word games. Just about every week there's a new app game to simultaneously test your vocab and index fingers. Lex is a compelling timed word game with intense music and kaleidoscopic presentation. Faced with a selection of nine letters that looks like a conundrum, you must pick three of them to form a word before each letter times out and evaporates. The countdown is shown not with a clock, but by the letters slowly changing colour. Every letter you get rid of is instantly replaced by another, creating an addictive, infinite loop of racing the clock and forming three-letter words. (Don't worry; the high difficulty level means that each game is a lot shorter than infinity.) Lex is surprisingly suitable for children, as swearing isn't allowed and it's blissfully free of in-app purchases. itunes.com/ie