System Jam
Unjam the street before your fuel runs out.
About System Jam
System Jam is a traffic-sliding puzzle: clear a path so the rickshaw can reach the right edge of the third row. Vehicles move along their own orientation and cannot pass through one another. Every square traveled costs one fuel, even when several squares are covered in one drag. This permanent teaching board explains how to plan space and count that cost.
Rules and tips
Find the blocker’s blocker
This example is separate from the daily boards. R is the rickshaw. A is a vertical bus, B and C are horizontal cars, and D is a vertical car. Repeated letters represent one vehicle; dots are empty squares. Rows and columns count from the top left. The fuel tank starts at 14.
A blocks the rickshaw at row 3, column 4. It cannot move upward because it already touches the top edge. To clear row 3 it must move down three squares, ending in rows 4–6. But B occupies row 4, column 4. Move B first. C and D do not obstruct the required spaces, so leave them alone.
Three slides, eight squares of fuel
Plan all three slides before moving. The numbers below count actions in this explanation; the game’s move counter counts squares traveled.
- 1. Slide B left one square, from columns 3–4 to columns 2–3 in row 4. Cost: 1 fuel; 13 remain.
- 2. Slide A down three squares, from rows 1–3 to rows 4–6 in column 4. Cost: 3 fuel; 10 remain.
- 3. Slide R right four squares, from columns 1–2 to columns 5–6 in row 3. Cost: 4 fuel; 6 remain. Reaching the right edge completes the board.
Compare an unnecessary extra square
Sliding B left two squares also opens column 4, but the second square does no useful work. Follow with the same A and R moves and the route costs 2 + 3 + 4 = 9 fuel, leaving 5 instead of 6. Both plans win on this board; the shorter one preserves an extra unit of fuel.
Eight is the minimum here: R must travel four squares to the edge; A must move down at least three to leave row 3; and B must move at least one to make that possible. Those necessary distances add to eight, and the demonstrated route achieves it. The teaching budget follows the daily rule of six extra fuel beyond the shortest solution.
Spend fuel on a dependency, not a gesture
In a daily board, work backward from the exit: which vehicle blocks R, and what prevents that vehicle from moving? Look for the specific empty squares needed by each blocking vehicle. Count the squares in each proposed slide before spending them.
Undo restores a position but does not refund fuel. Before undoing, ask whether the new arrangement can still support a complete route with the fuel remaining. A shorter-looking drag is not automatically cheaper, and a long drag is not one fuel: distance is what the tank records.