The Cat Room is a reflexive lattice polygon: it holds exactly one interior lattice point, where the cat sits.
Click a lattice point outside the room to add it as a new vertex (expansion); click one of the room's corners to cut it away (reduction).
Match the dashed outline exactly to clear the stage. Moves shows how many renovations you have made. Clear the stage within the target number of moves to advance.
A move that lets an extra lattice point into the interior, or squeezes the cat onto the boundary, is a slip: the room is numbed and the move rolls back.
Terminal mode. The Cat Room is a terminal polygon: there are no lattice points along its edges, except for the corners. In this mode, a renovation that leaves a point on an edge also counts as a slip.
Left click renovate · Right click undo
This is the academic edition. The full version is coming to
iOS and Android.