Choose a brick and a colour, then click or tap a square to place it. Raise the Build layer to stack it on existing studs. Green previews fit; red previews need a different spot.
Drag the board to turn the camera. Use Remove to click a brick away and Undo to recover a move. Test your creation to check the challenge and its connections.
Keyboard: arrows move the preview, Enter places, R rotates, [ / ] change layers, Backspace undoes. The test checks brick connections and route clearance; it is a playful rule system, not a structural engineering simulation.
Your builds save on this browser when storage is available. Save build also saves immediately. Restart clears only the selected challenge, and Undo can recover it.