The Cat Room is a canonical lattice polytope: it holds exactly one interior lattice point, where the cat sits.
Drag to turn the room around; scroll or pinch to zoom.
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 and advance — take as many moves as you need. Each cleared room scores 1 point, or 3 points when the finished room is reflexive (its polar dual is again a lattice polytope): a reflexive goal wears a tint of its own, and clearing it earns an extra chime.
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 polytope: its only lattice points are the corners and the cat's seat. In this mode, a renovation that leaves a point on a wall or an edge also counts as a slip.
Room corners that lie outside the dashed goal are tinted — they will have to be cut away sooner or later.
On a VR headset, press Enter VR: point with a controller and pull the trigger to renovate, hold the grip to grab the room — moving and turning it — and press A / X to undo.
Left click renovate · Right click undo · Drag rotate