@half.double: Surface crochet is much *much* easier than you think it is! it's literally just slip stitching! the only tricky part is identifying the best part of the existing stitch to slip stitch around, and with Tunisian crochet (which is what the base check blanket swatch is here) the stitches are super obvious. You can surface crochet over any stitch though! although something where the stitch is a relatively equal height and width (like single crochet) will be easiest for an even, outlined check pattern like this.