One of his ten top genre-twisting novels, as shared at the Guardian:
VALIS by Philip K DickRead about the other entries on the list.
Imitators of Dick often share this problem: that behind their carefully fracturing, multiplying realities is the sense of a rational, maybe even clever author in command of it all. In the best of Dick’s novels, you feel the author’s own grip on reality might just be as tentative as that of his suffering characters. In VALIS (probably his masterpiece) the distinction between science-fiction fabulism and autobiography collapses completely, as a character that is explicitly Dick experiences a great revelation on the nature of existence by way of a pink laser beam.
--Marshal Zeringue