Rail Yard Shunter is a free 3D train puzzle. You drive a small diesel shunter around a track with three sets of points, a siding, a run-around loop and buffer stops. Couplers work like springs: touch a wagon below the speed limit and it joins, hit it hard and the coupler springs open and costs points. Each shift asks you to couple wagons A, B and C to the locomotive in a set order, then stop the train in the marked departure zone within 120 seconds. A close-up shows the gap and your closing speed. There are 24 shifts that add hand-brake wagons, heavy wagons that brake slowly, a short siding for sorting and run-around moves.
The coupler springs open and you lose points.
The UTC date picks one shared shift, and only a finished train counts.
Yes, friends in a room play the same seeded shift.