Some 'best six - words novels' are extremely concise yet profound. For example, 'For sale: baby shoes, never worn.' It manages to convey a deep sense of loss and tragedy in just six words. The brevity forces the reader to fill in the gaps, using their own imagination to create a backstory.
The 'best six words novels' often play with the power of suggestion. They can be about love, like 'Met you. Loved you. Left you.' which sums up a relationship in a very minimalist way. Each word is carefully chosen to evoke maximum emotion with minimal verbiage.