Idea Expression Dichotomy in Copyright In Apps

As one commentator noted, a court found the following in the recent matter of  Tetris Holding v. Xio Interactive, 

"...the court held that game concepts, mechanics, methods of operation, rules and other utilitarian features are not protectable. However, the visual expressions, sequence of images, shapes, sizes, colors, sounds, characters and other expressive elements are all protectable unless such elements are somehow inseparable from the relevant game idea or function under the doctrines of merger or scènes à faire.

"... Xio’s Tetris clone was determined to be infringing since it copied almost every discrete element of Tetris including the shapes, colors and movement of the playing pieces, dimensions of the playing field, display of the next piece to fall, etc. The doctrine of merger did not apply because there are almost an infinite number of ways Xio could have otherwise expressed the essential methods of operation, rules and other utilitarian features of Tetris without copying all of the foregoing elements. Similarly, the doctrine of scènes à faire did not apply since Tetris is a unique puzzle game that does not have any elements that are mandated by a genre.

http://www.forbes.com/sites/oliverherzfeld/2012/07/10/thinking-of-creating-an-angry-birds-clone-read-this-first/?goback=%2Egde_69260_member_133043990