A logic puzzle drawn as an architect's plan in light and shadow. Fill cells with concrete so every number becomes a room of exactly that many floor tiles, each room holds one number, all the concrete joins into one structure and no 2×2 block is solid. Each block throws a long shadow across the sunlit plaster.
Site survey
Eight plan sizes from 5×5 to 12×12, drawn from a catalogue of 64 puzzles with one solution each, plus a generator for endless fresh plans.
Foundations · the timed trial
Every size has its own clock, longer for bigger plans. Finish before the light runs out and the plan is approved: you score ten points per row plus half the seconds left. Two solved trials open the next size, and your fastest time per size is kept.
Frame · the endless run
Fresh plans from 5×5 to 9×9 without end. The streak multiplies your points, but walking away from a started plan ends it.
Fit-out · the workshop
Spend points on four upgrades: Spare blueprints for an extra hint per plan, Inspector's lamp to light broken rules in red, Mason's seal to close finished rooms in one tap and Longer daylight for ten more seconds on the clock.
Inspection · statistics
Tiles for plans solved, points, success rate, longest streak, hints and trials, with a bar chart of recent solve times, a sparkline of points and a feed of recent plans.
Handover · plaques
Thirteen plaques to collect, from your first solved plan to a fully fitted workshop.
Maintenance · settings
Haptics, the building code, a progress reset and the animated background: concrete panels with slanted bands of sunlight crawling across them and dust floating in the brightest band. Switch the animation off for a still frame.
Plays offline, no account needed.