Killer
Cage totals with no repeated digits inside a cage.
BEYOND CLASSIC
Nine ways
to bend the rules.
Every variant is enforced by the game engine, candidate system and completion validator—not painted on top of a Classic board.
Diagonal X
Both long diagonals must also contain unique digits.
Hyper
Four extra 3×3 regions add another layer of uniqueness.
Jigsaw
Irregular regions replace the standard boxes.
Thermometer
Digits rise strictly from bulb to tip.
Arrow
Digits along the arrow sum to the circle.
Sandwich
Outside clues describe the sum between 1 and 9.
Kropki
Dots encode consecutive or double relationships.
Renban
Digits on a line form a distinct consecutive set in any order.