Wrapping a pure logic board inside 1920s mob case files is a great hook to keep players solving the next case. Since you stressed that no board requires guessing, I'm wondering if there's a hint system for when you get stuck that doesn't spoil the answer—like pointing you toward a new deducible clue instead of just filling a spot in?
Thanks! Yes, that's how the hints work. A hint never just fills in a square: it walks you through the next deduction a step at a time, which rule bites, where on the board, and what follows from it. You can close it at any step once you've seen enough and finish the move yourself. Give it a try and tell me if any hint feels like it gives too much away.