3D Protagon Puzzles
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How to Play

Tap a cell to walk it round the marks: ruled out, then confirmed, then clear. The Eliminate / Confirm buttons choose which of the two a tap puts on an empty cell.

Each tap marks only the cell you tapped — rule out the rest of a row or column yourself, one tap at a time.

Nothing is judged while cells are still open — the board is checked once it is completely filled, and wrong marks are named with the clue that rules them out.

Settle an item on two faces and the cell joining them on the third is decided — the hint points it out.

Tap a clue in the sidebar to light up the cells it can decide.

Drag to turn the cube; press 1–3 to fly to a face. Hint explains the next deduction.

Every puzzle has one answer and no guessing.

0 of 3 faces settled

3D Logic Grid

Game Stats
Clues
Confirmed
Eliminated
Time
Games Played
Difficulty
Controls
Clues
How to Play
Goal

Three categories, one answer. Every clue tells you how two of them line up; find the single arrangement that satisfies all of them. The pairings are spread over three faces of a cube, and the faces are tied together by deduction: settle an item on two faces and the third follows.

Controls
  • Tap a cell to walk it round the marks: ruled out, then confirmed, then clear. The Eliminate / Confirm buttons decide which of the two a tap puts on an empty cell — both marks are always one tap away, so nothing is out of reach.
  • Shift-tap (or right-click) places the other mark straight away, and Backspace clears a cell.
  • A tap changes only the cell you tapped — confirming a match leaves the rest of its row and column alone, so rule out the pairings you have disproved yourself.
  • The faces are joined by deduction, not by the board: when two faces agree about an item, the cell that links them on the third face follows. Get a Hint will point out a step that crosses faces and name both of them.
  • Tap a clue in the sidebar to light up every cell that clue can decide.
  • Drag to turn the cube, scroll or pinch to zoom, and double-click to return to the overview.
  • Press 1 2 3 to fly to a face and 0 for the overview. The face rail does the same.
  • Nothing is judged while cells are still open: the board is checked once it is completely filled, and wrong marks are named with the clue that rules them out.
Keys
← → ↑ ↓
Move around the grid
X
Eliminate mode
C
Confirm mode
Enter
Walk the focused cell round its marks
Backspace
Clear the focused cell
H
Hint, with the reasoning
U / R
Undo / redo
1–3 / 0
Focus a face / overview
Difficulty

Easy is a single 4×4 face, solved by reading a line at a time. Medium adds the other two faces at 4×4 and starts needing steps that cross between them. Hard and Expert run 5×5, and lean on either/or and if/then clues.

Tips
  • Confirm what a clue states outright first, then rule out the rest of that row and column yourself.
  • A row or column with one cell left undecided must be the match.
  • When a clue names items on two different faces, tap it — the cells it can decide light up.
  • Stuck? Get a Hint names the next cell and explains which clue forces it.
Shortcuts
Drag Rotate
Scroll Zoom
Double-click Reset view

About 3D Logic Grid History, Strategy & Tips

3D Logic Grid takes the classic deduction puzzle and lays it across three faces of a rotating cube. Each face carries one pair of categories; every clue tells you how two items line up, and exactly one arrangement satisfies all of them.

The reasoning is the same as the flat version, but the board does the bookkeeping: confirm a match and the rest of that line is crossed out for you. What is left is the part worth doing — reading a clue and working out what it forces, including the steps that only appear when you compare two faces.

The History of 3D Logic Grid

Logic grid puzzles were popularised in the twentieth century through puzzle magazines, with the famous “Zebra puzzle” as their template. The 3D variant spreads the deduction grid across the faces of a cube, so the pairings you are comparing sit on different planes and the puzzle becomes something you turn in your hands.

The appeal is unchanged: read the clues, mark what must be true, cross out what must be false, and watch the grid resolve itself through pure reasoning — no guessing required.

Solving Strategies

Confirm, then let it cascade

Mark a match as confirmed and the board clears the rest of its row and column on that face. You rarely need to eliminate anything by hand.

Let one face answer another

Each item appears on two of the three faces. Once you know where it sits on both, the cell that joins those two partners on the third face is settled — that is the step the cube exists for, and the hint will name the two faces it used.

Follow a clue across the cube

Click a clue in the sidebar and the cells it can decide light up — including on faces you are not looking at. Turn the cube or press a number key to fly there.

Single empty cell = certain

If a row or column has only one undecided cell left, that cell must be the match. The hint button will point it out and say why.

Read the either / or clues carefully

A clue such as “the astronomer used either the Spectrograph or the Oscilloscope” is only useful once you have ruled one of them out — and ruling one out is often worth more than confirming the other.

3D Logic Grid FAQ

Is this harder than the flat logic grid?
The logic is identical; the cube spreads the grid across faces you turn between. It adds spatial navigation, not new rules.
Do I ever need to guess?
No. Every puzzle in the pool is checked by a solver before it goes live: it has exactly one answer, and that answer is reachable by step-by-step deduction from the clues alone.
How do I mark a cell?
Tap a cell to rule the pairing out, or switch the mode toggle to Confirm and tap to mark it as the answer. Tapping the same cell again clears it. You never have to fill in the leftover cells to finish.
What does confirming a match do?
It crosses out the rest of that row and column on the same face, and carries the same pairing onto the other two faces, because all three grids describe one arrangement.
How does difficulty change?
Easy is a single 4×4 face. Medium adds the other two faces at 4×4. Hard and Expert run 5×5, and Expert leans on either/or and if/then clues.
Can I leave and come back?
Yes — your board, your timer and your hint count are saved as you play, and picked up again when you return to the same difficulty.