Social chess is a chess app for Android that lets you play chess with your friends. The app icon is derived from the iconset designed for the game, and uses two chess pieces placed next to each other.
Most chess apps use a very particular style of icons which have become the de-facto standard since they've been in use since the early days of computers. While this standardisation brings consistency to the experience, they aren't exactly the best looking icons.
While designing the icons for the app, there were some very distinct goals in mind - the icons had to look good in small squares, perform well across a range of android screen sizes and resolutions, and be clearly distinct from each other. There was another challenge as well - the black and white icons both had to look good on dark as well as light squares.
The final icons were designed as vectors in Illustrator, and went through a series of refinements based on in-game testing. A white outline was added to the black shapes, and vice-versa to make sure the icons stood out on squares of both colors.