DEDUCE

• This is the sit-down puzzle — a good solve takes a few minutes, and beating seven earns a bonus. No rush: step away any time and your grid keeps, clock paused.
• Four people, and three things to work out about each one. Every value is used exactly once down a column.
• Each cell starts with every possibility. Tap one to cross it off. When a single possibility is left, that cell is settled.
• Sure of one? Double-tap it. The rest of the cell crosses off, and so does that value for everyone else in the column — one move, and one Undo brings it all back.
• The clues never tell you an answer outright — they rule things out. Tap a clue to gray it once you have used it; it folds away at the top of the list, so the clues you still need stay next to the grid. Tap the “used” line to open them, and tap a grayed clue to bring it back.
• One column is ordered, and it reads as a list, not a picture: top to bottom, lowest first. So floor 3 sits above floor 6 on screen — "a lower floor" means further up the column, and "two floors after" means further down.
• There is exactly one arrangement that fits, and you can always reach it by crossing off. You never have to guess.
• Fill every cell, then hit Check. You get three checks — run out and the answer is shown — green where you had it, red where you didn’t — and you keep credit for the cells you had right.
• Cross something off by mistake? Tap it again to bring it back, or use Undo to step back through your crossings-off one at a time.
• Talked yourself into a corner? Reset clears the whole grid, your notes and any hint clues, and gives the three hints back. Tap it twice — it asks first. The clock keeps running, and hints you have already taken still count.
• Stuck? Hint gives you an extra clue — you still have to apply it. There are three per puzzle, and that is all. If you had ruled out something a new clue says is true, it puts that back. Hints are counted, not punished.
• Leave the page and the clock stops. It starts again when you press Continue, not when you come back.

Read the full guide, with strategy