Who's Knockin' is a logic puzzle (or set of possible puzzles) with the same form as the (probably apocryphal) Einstein Puzzle, also known as the Zebra Puzzle. It's a fun and challenging puzzle to solve even if you don't have a degree in predicate logic. The trouble is, if you've solved it once, you always know what the answer is. Not so any more!
If Who's Knockin' merely randomised the names of all elements in the puzzle, then you'd always be able to guess the answer just by looking at the form of the clues: if, for instance, the woodworker is always the person that lives in the second house, you could guess it every time just by looking at the clue saying who lives in the second house. What the game engine does is randomly pick one of five possible puzzle structures (all sharing some identically structured clues), and then it randomises the order in which the clues are listed. This essentially means the game can't be 'gamed', you have to figure it out afresh each time.
While it lacks literary qualities and breadth of response, the game more than achieves what it sets out to achieve: a challenging and unique puzzle with every play. And that's not something many games can boast, let alone one move games.