As if regular 2D sudoku weren't hard enough, Kuboku adds a third dimension to the popular puzzle game. Instead of a 9x9 grid, Kuboku utilizes an 8x8x8 cube.
The concept is basically the same, where only one digit of a given value can occupy each line and its sub-grid. In this case, the sub-grid is the 2x2x2 cube within the whole.
Don't be intimidated by the new format. The makers of Kuboku reassure us that there are many levels of customizable difficulty, so even beginners can play matches that will only take them minutes to solve.
Kuboku is available now in the App Store for US$1.99, and includes a generous 1000-level set.
source: Kuboku via Gizmodo