Jenga doesn’t seem a natural fit for an app, but NaturalMotion does a terrific job of building an electronic version of this classic — thanks in large part to its terrific physics engine, which causes the blocks to react as they would in the real world. Is it more fun than the game you play with friends around a table? No. But it’s as close as you can come. The pass and play mode is the best mode — since playing Jenga alone isn’t a fulfilling experience. And the new arcade mode, with colors and a timer, is a great spin on the single player game that makes it fun to play when you’re alone. Game Center functionality or some other way to play with friends who aren’t in the immedate room would have been welcome, but at its core, this is a terrific game.