functional is a puzzle game about math and abstraction. Solve problems and reuse your solutions to write ever-more-complex logic.
Start with the simplest mathematical primitives. Everything is a function, and functions can be used to build everything else.
Use your previous solutions as black boxes, and use them as building blocks to build more complex solutions.
Compare your solutions against other players, and against your Steam friends, both in efficiency and simplicity.
Create your own levels and share them with the community.