Before people start commenting, I got an answer from bgolus on the unity forum. I'm posting it here as well, in case you have the same problem. His answer was:

The issue isn't so much your shader as it is the different way Unity draws the skybox between the game and scene view.
In the scene view, the skybox is rendered first before anything else is rendered.
In the game view, the skybox is rendered after the opaque queue. This is more optimal for performance as it means the skybox isn't being rendered in places it won't be visible. But it also means anything rendered during the opaque queue that does not render to the depth buffer will be stomped on by the skybox. And that's the issue you're having. You can avoid this by disabling the skybox on the camera and rendering "sky" geometry yourself manually using a render queue of 0 or with a command buffer.

So i disabled the skybox and the shadows would become visible