About Grades
In a crystal cavern, an illuminated ledger holds numbered gems. Brass runes count the gems in each row and column; sapphire runes add their values.
Explore 160 original charts from 4×4 to 7×7 in four shelves. Every chart has one solution, and even diagonal gem contact is forbidden.
The clock starts when you open a chart. Your first solve stays on this device; an uninterrupted first session can set the verified best time shown with its holder.
How to play
- Goal
- Place gems numbered 1–9 so the edge clues give each row and column's gem count and value sum, and no two gems touch, even diagonally.
- How it ends
- A chart completes when every count, sum and separation rule holds; there is no loss.
- Record
- Your first solve time is kept per chart, and the fastest verified first solve appears with its holder.
- Place gems numbered 1–9. The clue above a column and left of a row is its gem count; the clue below a column and right of a row is its digit sum. Gems may not touch by side or corner. The worked ledger shows gem 2 blocking a diagonal neighbour while gem 3 belongs two rows away.
- Tap a cell to select it, then tap a digit. Tap the same digit or Erase to clear it, or Cross out a cell you know is empty. The edge clues glow when they agree with your marks.
- Undo reverses a mark. Restart clears marks without resetting the clock. Check names conflicting clues and ends ranking for that attempt. A chart completes when every count, sum and separation rule holds; there is no loss.
Controls
| Input | Action |
|---|---|
| Tap / click a cell | Select the ledger cell |
| Tap a digit 1–9 | Place or remove that numbered gem |
| Cross out | Mark an empty cell |
| Erase | Clear the selected cell |
| Arrow keys | Move focus through the grid |
| 1–9 | Place a gem at the focused cell |
| X | Cross out the focused cell |
| 0 / Delete | Erase the focused cell |
| Z | Undo the last mark |
| R | Restart without resetting the clock |
| Escape | Close a panel |
Good to know
Use digits from 1 to 9. Progress and reduced motion save in this browser; sound uses the shared site setting.
