Sumplete
Sumplete flips the usual order of puzzles: instead of writing numbers in,
you have to take them out. An N×N board is filled with numbers, and the
edges hold targets — the sums that must remain in every row and column
after your removals. Tap a cell — it is marked for removal and fades to
gray. Tap again — it comes back.
The best part of the genre is the live feedback: the edge targets light up
on the fly. A row matched — teal; unmatched — red. Every mark changes two
targets at once: its row and its column, and that intersection is the whole
game. A small row target almost shouts which numbers must survive, while a
big one makes you restore what looked expendable.
Every round is generated on the fly: numbers are scattered first, then some
cells are secretly marked for removal, and the targets are computed from
what remains of that hidden solution. The puzzle is guaranteed solvable —
and usually in more than one way, which is a bonus for a puzzle.
Three sizes: 4×4 to get acquainted, 5×5 for an evening, 6×6 for a full
challenge. Winning earns points — the bigger the board, the higher the
reward. Input is tuned for phones: tap a cell, no dragging.