It is because they hope to create a crowd-sourced game later down the road. The idea is that by releasing the source they can hold contests to create levels and

It is because they hope to create a crowd-sourced game later down the road. The idea is that by releasing the source they can hold contests to create levels and bosses and music and therefore create a finished product with minimum effort. source: http://frozenbyte.com/blog/?p=176 http://frozenbyte.com/blog/?p=176