Fifty Levels

The campaign runs from open ground with room to spare to boards where the wall budget is barely above the theoretical minimum.

That minimum is not a guess. For any level there is a smallest number of cells that must be walled to separate the front from the edge — a number that can be computed exactly, and below which no ordering of moves can ever win. Every level’s budget is set relative to it, and the margin narrows as the campaign goes on. Difficulty here is a property of the board, not a feeling.

Every level ships with a winning line attached, which is replayed through the game’s own rules before release: each placement legal when it is made, the budget respected, the front sealed at the end. A level that no longer passes that replay does not ship.

Levels where doing nothing would already win are rejected outright — that is not a puzzle.