Pips December 16, 2025

Hints and answers for December 16, 2025

Stuck? Take it in stages. A nudge costs less than the full answer, and the answer is here if you want it — each diagram below is the verified solution our generator built this board from, using tiles drawn from the standard double-six domino set. On the looser boards other valid arrangements can exist too; any filling that covers every square and satisfies every region counts as solved.

How the three boards differ

These are three separate boards, not one board with hints removed, so playing all three on December 16, 2025 gives you three genuine attempts rather than three views of the same solution.

easy

8 squares, 4 dominoes, 3 regions, 2 region boundaries. 33% of its regions carry something other than an exact total, and the widest region spans 4 squares.

medium

14 squares, 7 dominoes, 6 regions, 6 region boundaries. 50% of its regions carry something other than an exact total, and the widest region spans 3 squares.

hard

20 squares, 10 dominoes, 7 regions, 11 region boundaries. 57% of its regions carry something other than an exact total, and the widest region spans 4 squares.

The arithmetic check

Your tray carries 58 pips in total, and the exact-sum regions between them demand 30 across 9 squares. That leaves 28 pips to absorb elsewhere. Running that subtraction before you place anything tells you whether the unconstrained squares are going to be a dumping ground or a tight squeeze.

The same check on the medium board: your tray carries 29 pips in total, and the exact-sum regions between them demand 17 across 9 squares. That leaves 12 pips to absorb elsewhere. Running that subtraction before you place anything tells you whether the unconstrained squares are going to be a dumping ground or a tight squeeze.

Where this puzzle comes from

This board was not hand-designed and it was not copied from anywhere. The generator laid down a valid arrangement of 10 dominoes first, then divided the 20 squares into 7 regions and derived each region's rule from the values that had already landed in it. Because the solution existed before the constraints did, this board provably has one.

It was then loosened: rules were swapped for weaker ones, one at a time, keeping each swap only while the number of valid arrangements stayed inside the bound for this difficulty. That is why 4 of the hard board's 7 regions carry something other than an exact total.

Generation is seeded from the date, so December 16, 2025 produces this exact board on every device, permanently. Sharing this link always shows the same puzzle. More on the process in our editorial policy.

What's on these boards

What goes wrong on this one

The all-different region is the one to watch. With 4 squares in the widest region on this board, an all-different rule quietly forbids far more arrangements than it looks like it does.

With 3 exact sums on the board, there is usually a square that only one tile in your tray can legally fill. Find that square first and the rest tends to cascade.

If you have genuinely stalled, undo back to the last tile you were confident about rather than reshuffling everything. Most dead ends on a board this size trace to one early placement made on a guess, and everything after it inherits the mistake.

How much the regions overlap

There are 11 distinct region-to-region boundaries on this board, which is a lot for 7 regions. Almost every tile you place is going to land half in one region and half in another, so treating regions as separate sub-puzzles will not work here — think in pairs.

A domino can straddle two regions, and each half only has to satisfy the region it lands in. That is the single most common misreading of the format — people assume a tile must sit inside one region, which makes perfectly solvable boards look impossible. The rules page works through it with examples.

The badges on this board

The hard board uses 4 of the six possible region rules. What each one is actually demanding here:

= 13

Spreads exactly 13 pips over 4 squares, an average of 3.3 each. Anything that pushes the running total past 13 is already lost, so this is the region to count before you commit.

=

Forces all 3 squares to show the same value. With distinct tiles in your tray, only a narrow set of combinations can supply that.

≠

Forbids any repeat across its 1 squares. Note that this constrains values, not tiles — two different dominoes both contributing a 4 still breaks it.

< 4

Caps every individual value below 4, which rules out roughly 43% of the pip values outright. It says nothing about the total.

The full badge vocabulary, including the ones this board happens not to use, is on the pips rules page.

What your tray forces

The tray holds 4 doubles (1-1, 0-0, 4-4, 5-5), and the board has 2 regions governed by an equality rule. A double can never sit entirely inside an all-different region, so those tiles have to straddle a boundary — which usually pins them down before anything else on the board.

The heaviest tile on the hard board is the 5-5 and the lightest is the 0-0. Those two are worth locating first: the heavy tile can only go where a sum has room, and the light one is often the only thing that fits a tight region.

Why the shape matters here

This is a distinctly irregular outline, filling only 67% of its 6×5 bounding box. Narrow arms are the danger: a square at the end of a one-wide corridor has exactly one possible partner, so if that partner gets covered the board becomes unsolvable regardless of what else you do.