Nike Training Club app (cool), an animated and annotated globe, Barefoot World Atlas (crack for map heads) and a pretty impressive Leonardo da Vinci: Anatomy app. Then they showed me Spelltower—the “killer app.” Okay, it’s a killer app if you’re a word-nerd whose idea of bliss is playing serial games of old-school Scrabble on weekends. On review sites, it’s often described as being “furiously addictive.” This Boggle-meets-Tetris app takes seconds to learn. As you find words, the tower of letters crumbles, leaving you with fewer and fewer letters to use. To master the game, it takes—in the words of Zach Gage, Spelltower's designer—all your “lexicological wits and tactical know-how.” Gage, a designer, programmer and conceptual artist from New York, is the mastermind behind this game as well as Halcyon, Bit Pilot and Unify. Unlike his dedicated acolytes, Gage, apparently, isn’t even into word games. "Making games in a genre that I don't enjoy is a lot of work, but it’s also an incredible amount of fun,” he told an interviewer for Arstechnica. “I'm a big proponent of 'Outsider Art,' and I think the same tenets apply to game design. Doing something I don't understand keeps me focused because I'm learning so much and everything is so exciting. It also affords me the possibility of stumbling on something new that nobody's ever tried before." I scored a modest 788 on my first attempt and dropped to 563 the second round—which only fuelled my ambition. Third time was a charm—I clocked out at 1,117. “Quiet” netted me 310 points and a “superb achievement” electronic shout-out. For the next hour, I entered a delicious time warp. Turns out I did have time for this app!