The Doppit Almanac · No. 49
Blockit, a daily Doppelblock puzzle
Two blocks a line, and the gap adds up
What it is
Blockit is a number placement puzzle, known elsewhere as Doppelblock and as Sumaddle. Every row and every column holds two blocks, and the cells left over hold the numbers 1 upward, two fewer of them than the grid is wide, each one once in every line. The total beside a line adds up its gap, the cells lying strictly between that line's two blocks.
Placing the blocks is the puzzle, and the totals are what you place them by. A total that takes every number the line has pushes them out to the ends, and a total of 0 puts them side by side.
How it plays
- Put two blocks in every row and every column.
- Fill the cells left over with numbers, each one once in every row and column. The rack shows which ones the board uses.
- A total counts the gap alone. Numbers outside the two blocks add nothing to it.
- A total of 0 means the two blocks touch.
- A line can show no total at all. A hidden total asks nothing of its line.
- Pick a number or Block from the rack and tap a cell. Tap it again to clear it. Notes pencils in what a cell might hold.
- A line that can no longer be filled turns red, and so does any total beside it. Hint gives the next forced mark and says what forced it.
The difficulties
Easy is four cells across, so every line takes two blocks and the numbers 1 and 2, and nothing there asks you to suppose anything. Medium is five across with the numbers 1 to 3, and once or twice a board you have to suppose. Put a number in a cell, follow what it forces, and wait for a rule to break: a line that can no longer be filled, say, or a total its gap can no longer reach. Then that number is out. Hard is six across with 1 to 4 and wants that move up to eight times. Expert is six across too, and the size is not what changes. Every expert board has a place where reading the lines settles nothing, and one supposition settles nothing either. What breaks it is a supposition inside a supposition, which no board below expert ever needs. A fresh board is dealt every day, for nothing.
Play today's board