You get a target position. Find the moves that led there: 3 moves by White and 3 by Black, played from the position on the board. You have 5 attempts.
Some cases start from the opening position. Midgame cases start from a position after a real opening, with White to move.
Opening cases are Normal, midgame cases are Extreme. A missing piece means it was captured. Moves don't have to be good — they just have to lead to this exact position. Expect pieces that move and come back, captures that leave no trace, and checks that force the order.