THE SHORT VERSION
Sumplete: a grid pre-filled with digits. Delete some of them so that the remaining digits in each row and column add up to the target shown at the edge. Nothing to calculate about which digit goes where — you're deciding keep or delete.
Kakuro: a crossword-style grid with empty cells. Every across and down run has a sum target. Fill the empty cells with digits 1–9 so each run hits its target and no digit repeats within a run. You must figure out which digits work — they aren't given.
Both use arithmetic. The fundamental difference is direction: Sumplete subtracts from a full grid; Kakuro builds up an empty one.
SIDE BY SIDE
Starting state
Sumplete: all cells filled — you delete
Kakuro: all cells empty — you fill
The question
Sumplete: which digits to keep vs remove?
Kakuro: which digits belong in each empty cell?
Sum targets
Sumplete: one target per row + one per column
Kakuro: one target per across run + one per down run
No-repeat rule
Sumplete: none — the same digit can stay in multiple cells
Kakuro: each run must contain distinct digits (no repeats)
Digit range
Sumplete: fixed grid with pre-set digits (any value)
Kakuro: you choose from 1–9, subject to run constraints
Grid shape
Sumplete: rectangular grid (typically 3×3 to 7×7)
Kakuro: irregular crossword layout
WHAT STAYS THE SAME
Both puzzles are fundamentally about satisfying sum constraints on a grid. In both cases, the target for a row (or run) tells you the total that must survive, and you work backwards to decide which cells achieve it.
Both reward scanning for rows and columns that are nearly forced. In Sumplete, a row where the deletion amount almost equals one digit's value is close to a forced keep/delete. In Kakuro, a short run with a high or low sum target has very few valid digit combinations — both lock down quickly.
Neither puzzle requires guessing. Both are solved entirely by deduction when approached systematically from the most-constrained rows or runs first.
HOW THE ARITHMETIC DIFFERS
Sumplete's arithmetic is subtraction: the target tells you how much of the row's total must survive. Compute row sum − target = deletion amount. You need to find a subset of digits in that row that adds up to the deletion amount. The given digits are fixed — you don't choose their values.
Kakuro's arithmetic is enumeration: given a sum target and a run length, you list every combination of distinct digits from 1–9 that adds up to the target. A 2-cell run summing to 9 can be 1+8, 2+7, 3+6, or 4+5 — you narrow down which combination fits. This combination step is unique to Kakuro; Sumplete never requires it.
Kakuro also has the no-repeat rule: once you know which combination fits a run, the intersecting runs further constrain which cell gets which digit. Sumplete has no equivalent — the same digit value can stay in several cells without restriction.
WHICH IS HARDER?
Sumplete is a shorter path to a first solve. There's no combination-enumeration step, no crossing-run logic, and the grid is typically smaller. A beginner can pick up the deletion mechanic and reach a solved state in a few minutes.
Kakuro has a steeper arithmetic ramp. Internalising the common two-cell and three-cell sum combinations (e.g. a 3-cell run summing to 6 can only be 1+2+3) takes practice before the solving pace feels natural. Harder Kakuro puzzles require tracking multiple intersecting constraints simultaneously.
If you enjoy Sumplete and want a bigger arithmetic challenge, Kakuro is the natural next step. If Kakuro feels overwhelming, Sumplete builds the "target the total" instinct without the additional complexity.
WHEN TO MAKE THE SWITCH
If you play Sumplete: try Kakuro once you want to add digit placement and combination enumeration to your toolkit. The sum-targeting instinct transfers; you're adding one new mechanic (which digit combination satisfies this run?) rather than a new way of thinking.
If you play Kakuro: try Sumplete when you want a faster-paced sum puzzle without the combination enumeration step. Sumplete also offers a satisfying reverse-engineering flavour that experienced Kakuro players often find immediately intuitive.