PuzzlePeak Logic Quest — 60 Challenge Cards

Sixty challenges on wipe-clean cards, graded across four difficulty bands, played solo on a compact 5 x 5 board. Early cards can be solved in a minute; the last ten are genuinely hard for adults, which is what keeps the game in use past the first fortnight.

The board has a snap-shut lid and the pieces store inside it, so it survives being thrown in a school bag or taken on a train.