Today, the growing platform fragmentation has become one of a game developer's key concern.
Engines such as Unity have gained strong popularity as a viable assistance in addressing the issue.
However, they only solve part of the equation: regardless of the supported platforms, games often tend to live in silos, either per device or per platform. The reality shows that most of us have multiple devices on which we play the same games - and also that our friends don't necessarily own the same devices as we do. All the same, being able to play with them regardless of the device used, is crucial in making a game more fun through social means.