Clarify in what form the digital download is delivered

On the preorder page it is not specified how the digital download will be delivered.
Is it a Steam key or a Gog key or a direct download?
Can you choose between options?

I think that should be mentioned.

Either Steam or GOG you will choose. It will be either near release or on release.
You can find it on kickstarter page at least. Also FAQ has it will be GOG and Steam.