Where are the clickable places?

Hint 1 of 7:

Try the edges of everything.

Hint 2 of 7:

The four holes in the ground abound with items.

Hint 3 of 7:

The top edge of the screen is good.

Hint 4 of 7:

Try the right screen edge, and the bottom.

Hint 5 of 7:

Try the left horizon line.