A single, 3-stitch slanted decrease is all you need at the center of every second row to create a delightful mitered corner. That one stitch does all the work.
Add a hardworking multicolor yarn, and the appearance is complex although the stitching isn’t.
Weaving in ends isn’t much of a chore because each new square is attached to the next with a join-as-you-go technique. Work in your other loose ends as you stitch … and you’re golden.