Each floor is a full Sudoku: every row, column and 3×3 box holds the digits 1–9 — so every row adds up to 45.
The steroid: the three digits stacked in every vertical shaft (the same square on Floors 1, 2 and 3) must all be different and add up to exactly 15. Solve all three floors and make every shaft agree to clear the building.
⏰ The Building Shift: every hour, ONE floor swings 90°. The countdown above names the floor that will move. The printed givens are the building's foundation — they never move — but your entries and notes on that floor swing around them, so its shafts pair up with new neighbours and finished shafts come apart. Be ready to repair the equation. (The foundation never moves, so the building can always still be solved — no dead ends, ever.)