Drei HD

$3.99, iPad, iPhone, iPod Touch (iOS 6.0 or later)

Teaches: spatial relations, building, science, forces

CTR Rating: 88%

CTR Review

This leveled collection of 48 block stacking challenges each starts with a simple looking objective, but involves some very complex trial and error problem solving with some of the levels requiring collaborative play. The more levels you unlock, the more features you encounter. Some of the blocks disappear; other explode and some of the puzzles let you solve collaboratively with another player somewhere in the world. At first our app kept giving us a "server error" message. Later, other avatars showed up. A communication tool allows you to "speak" to other players using localized text bubbles that say such things as "hi" and "help." The social building aspects of this app are innovative and very interesting. What is most exciting about this set of puzzles is the planning and spatial reasoning that you need to have in order to solve each problem. Some of the levels are very hard, or impossible if you don't have an online connection. This could lead to unnecessary frustration. Also noteworthy: the sounds, which happen when shapes are moved, creating a type of living musical mobile. The aesthetics make this app worth a second look. Created in Switzerland by Etter Studio in October 2013. Drei has no reading or narration. The menus are in 18 languages: Arabic, Chinese, English, French, German, Greek, Hindi, Italian, Japanese, Korean, Portuguese, Rhaeto-Romanic, Russian, Spanish, Swedish, Swiss-German and Turkish.