This collection of Clifford Simak's "Golden Age" works is varied, presenting a couple or three little gems and then some less shining examples.
"Time Quarry" filling almost half the book, rambles disjointedly and magically throughout the Universe, questioning destiny as a driving force in creation. "Empire also suffers from an aggressive but dispersed story-line, and appears to be where Simac practiced his time-travel theories. These two represent the missing stars in my rating.
"The Street that Wasn't There", co-written in the early 40's is a more focused offering, with one prime character and a chilling philosophical interpretation of our reality, "as we see it", or don't. "The world that couldn't be" is an excellent story written in 1951 that was the best read for me out of the whole book. Well worth the .99 cents it is riveting, spine-chilling, and sure to keep your attention. Read "Hellhounds" if you must, knowing that it is not worth the pixels it was printed with. However, "Project Mastodon" saves the day, whichever day that saving is to happen, or was to have happened, or has already happened.