How to play
- Goal
- Fill every empty stone with a positive whole number so each upper stone equals the two touching stones below it added together.
- How it ends
- A pyramid is sealed when all stones are filled and every sum is correct; there is no loss.
- Record
- Your first solve time is kept for each pyramid, and the fastest verified first solve appears with its holder.
- Choose a numbered pyramid. Every upper stone must equal the two touching stones beneath it added together. In the worked example, 2 and 3 force 5 above them. If 5 and 2 are given, subtract to find 3.
- Tap an empty stone, type its number using the keypad or keyboard, then Set stone. A gold thread marks a group whose sum agrees; a red stone shows a full group that needs correction. Undo, Erase stone and Restart let you revise entries.
- Fill every stone and satisfy every sum to seal the altar. The clock begins when a pyramid opens and continues through shelf visits and Restart. Only your first solve can set a verified time; replays are practice.
Controls
| Tap / click | Choose a stone, enter digits, then Set stone |
|---|---|
| Number keys · Enter | Type and set the selected stone |
| Arrow keys | Move between stones |
| Backspace · Delete | Edit the draft or erase the selected stone |
| Z · R | Undo or restart; the clock continues |
| Escape | Close a panel or return to the shelf |
| Gamepad | Move the focus, open the number pad with A, set a stone, undo with left shoulder |
Tips for Number Pyramid
- Work both ways An upper value minus one known lower value gives the other.
- Follow the threads A gold thread means all three stones in that sum agree.
All 160 charts are fixed, unique and independently proved by an exact-rank solver and a no-guess deduction trace. Your progress and first solve time stay in this browser. A ranked time needs an uninterrupted first attempt on the game page. The game has no ads or analytics.
Watch how to play
About Number Pyramid
At the observatory, weathered ivory stones form a counting altar. Each upper stone holds the sum of its two touching neighbours below. Carve the missing numbers, and correct sums kindle threads of starlight.
Choose from 160 fixed pyramids in four shelves. Begin with straightforward addition, then work backward with subtraction through longer chains. Every chart has one independently verified answer and a route that needs no guessing.
