ShiftMaze

What you see

Each trial is one square board, from 6 × 6 up to 9 × 9 cells.

• The ball is your piece. The arrow keys, or the arrow buttons under the board, roll it one cell per move. A direction that is blocked is greyed out and does nothing.
• The goal square is where the ball must end. The trial is solved the moment the ball arrives.
• Walls (the solid squares) never move. They only appear in the inner cells; the outer ring of the board is always open floor.
• Crates move only when you push them. Stepping into a crate slides it one cell in the same direction, and the ball takes its place, but only if the cell beyond is empty floor inside the board. You cannot pull a crate, and you cannot push two crates at once.
• Moves: the pill shows the moves you have used against the move limit. On levels 1 to 3 the question above the board also states the length of the shortest route.
• Restart (R) resets the whole board. There is no undo: a push stays pushed unless you restart from the beginning.

A practice session opens at difficulty 3 and adapts from there. There is no countdown, but a clock in the side panel records your time. Press Enter to check your answer once the ball is on the goal, or when you decide to submit what you have.

How the levels change

Every board is checked by a full search of all ball-and-crate positions before you see it, so it is always solvable, and the shortest route is exact. From level 2 onwards the generator keeps a board only if its shortest route pushes at least one crate. That does not always mean the crate blocks every other path; often the push is simply a shortcut. Either way, the fastest solution involves moving a crate, so you have to think about where it will end up.

What it measures

ShiftMaze feeds the irreversible decisions facet of your planning score, weighted 28% on the planning shelf. In our game's own definition it draws mainly on planning and sequencing, with a spatial component.

It belongs to the family of push puzzles that started with Sokoban, created by Hiroyuki Imabayashi in 1981, in which boxes "can only be pushed, never pulled" and a careless push can trap a box for good. That family is hard in a precise sense: deciding whether a Sokoban level can be solved at all has been proved PSPACE-complete. The difficulty is not the size of the board but the fact that some moves destroy options permanently.

This connects to two findings from the planning literature. Patients with prefrontal damage struggled on tower puzzles mainly because they could not see or resolve a goal-subgoal conflict, a pattern the authors linked to failing to inhibit a strong but wrong response. And in healthy adults, tower performance related most strongly to inhibition among the core executive functions. In ShiftMaze the strong but wrong response is the straight line to the goal, and the inhibition is stopping before the push that ruins the board.

Unlike Towers of London, where every move can be undone, here the cost of a bad move is not just one extra move. It can be the whole trial. That is why we treat it as a separate facet.

How it is scored here

Only your final run counts. Restart wipes every move you made before it, and moves after the ball reaches the goal are ignored. Blocked directions are simply not recorded.

• Goal reached in the shortest number of moves: Correct, full credit.
• Goal reached in more moves: Partly correct, with credit equal to the shortest route divided by your moves. A 10-move maze solved in 14 moves earns about 71%.
• Goal not reached: Incorrect, with up to 40% credit in proportion to how much closer the ball got to the goal at its best moment. Here "closer" is measured as a straight count of rows plus columns, ignoring walls, so it is a rough measure and a small consolation, not a strategy.

In an adaptive session, Correct moves you up a level, Partly correct holds your level, and Incorrect moves you down one. Your game score combines credit with a small time component (15% of the weight), with expected thinking time growing with difficulty. Difficulty is measured from the board: half a point per move of the shortest route, 1.2 points per crate, minus a little when the move limit is generous. Crates count heavily because every push is a commitment. On our scale, 50 means you clear mazes at the rate their difficulty predicts.

Your session report shows committed mistakes (extra moves as a share of all your moves), mazes cleared, positions you could not recover from (runs that ended without reaching the goal) and step efficiency.

Where you will meet it

The closest relative in hiring is Aon's motionChallenge, part of its smartPredict gamified suite, which Aon says "measures complex planning capability". Prep sites describe it as sliding blocks out of the way to bring a ball onto a target cell. That is a sliding-block puzzle rather than a push puzzle, but the demand is the same: see the route and the block moves before you commit. Candidates also report a "Motion Challenge" in Capgemini's game-based aptitude round; Capgemini's own recruitment page describes only an online aptitude test covering logical reasoning, verbal and quantitative skills. ShiftMaze is the same family of task as these, not a copy of any vendor's game.

The method

1. Find the goal's doorways

   Look at the four cells around the goal. Which of them can the ball actually reach, and which are walls, board edge or crates? The ball must arrive through one of these doorways, so they are the true end of your route.

2. Trace the no-push route and count it

   Treat every crate as a wall and find the shortest path to a doorway. Count the moves. This is your safe baseline, and on many boards it is already close to the shortest route.

3. Look for a push that saves steps

   Now look for crates sitting on or next to a shorter line. For each one, ask where the crate would land after each push you need.

4. Run the four deadlock checks before any push

   Before a push, check the cell the crate will land in:

   • Corner: two blocked sides at right angles (wall or board edge). A crate there never moves again.
   • Edge: against the board edge, a crate can only slide along that edge.
   • Pair: a crate directly behind another crate cannot be pushed in that direction.
   • Goal: a crate on the goal square has to be pushed off again, which is impossible in a corner.

   If the crate would end up jammed in the way of your route, the push is a trap.

5. Compare with the move limit

   On levels 1 to 3 the question tells you the target. From level 4 the move limit gives it away: the limit is always the shortest route plus a fixed slack, 4 at levels 4 and 5, 3 at levels 6 and 7, and 2 at levels 8 to 10. If your plan is longer, look for another push shortcut.

6. Execute, and restart early if a push goes wrong

   Carry out the route. If you realise a push has jammed the board, press Restart at once. Your earlier moves are discarded completely; only time is lost, and every extra move you take on a doomed run is wasted.

Worked example 1: a crate in the gap

Show the solution

Doorways: the goal is on the top edge, so the ball can enter from the left, the right or below.

No-push route: treat the crate as a wall. The only gaps in the wall row are at the far left and far right edges, so the ball must go around: 8 moves.

Push shortcut: the crate sits in the one inner gap, directly between the ball and the goal. Rolling up pushes it: first move up is free, the second pushes the crate one cell up, the third pushes it onto the goal square.

Deadlock check: a crate on the goal is only fatal if it cannot be pushed off. The goal is on the top edge but not in a corner, so the crate can still slide sideways. Move left, move up, then roll right: the ball pushes the crate off the goal and lands on it.

Up, up, up, left, up, right: 6 moves with 3 pushes, 2 fewer than the walk around. If the goal had been in the corner, the same third push would have ended the trial.

Worked example 2: the straight line that is a trap

Show the solution

Doorways: the goal is in the top-right corner. It has only two neighbours: the cell to its left and the cell below it.

The tempting line: straight up is four moves. The first is free, the second pushes the crate one cell up, and the third pushes it into the corner, onto the goal. A crate in a corner can never move again. The maze is lost after three moves.

Stopping halfway does not help much: after one push the crate sits directly below the goal, blocking that doorway. You then have to walk all the way round: 14 moves in total.

The shortest route never touches the crate: go left along the bottom, climb the left side of the wall block, cross the top row and enter the goal from the left. Left, left, up, left, up, up, up, right, right, right: 10 moves, 0 pushes.

Notice that the move limit does not warn you here. The trial is lost on move three, long before the move limit runs out. That is what makes irreversible decisions different from ordinary inefficiency.

Tips and traps

Levelling up

Boards grow from 6 × 6 to 9 × 9, walls thicken from 8% to 18% of the inner cells, crates increase from none to four, and the spare moves shrink from eight to two. At the top levels, with two spare moves and four crates, a single careless push usually costs the trial or its full credit.

• Levels 1 to 3: use the shortest route stated in the question. If your route is longer, a push shortcut exists. Find it.
• Levels 4 and 5: work out the shortest from the move limit minus 4. Practise the deadlock checks until they are automatic.
• Levels 6 and 7: three crates can block each other. Watch for pairs: two crates in a line cannot be pushed along that line.
• Levels 8 to 10: with two spare moves, plan the whole route before the first move, including which crates you will not touch.

1. Week 1
   • Three sessions of 10 minutes
   • Before each first move, find the goal's doorways and the no-push route
   • Target: every maze cleared at levels 1 to 3, matching the shortest route in the question
2. Week 2
   • Three sessions
   • Say the landing cell of each crate out loud before pushing it
   • Target: no runs lost to a corner or edge jam
3. Week 3
   • Three sessions
   • At level 4 and above, work out the hidden shortest from the move limit
   • Restart immediately when a push goes wrong, and note why in one line
4. Week 4
   • Four shorter sessions on consecutive days
   • Plan the full route, including untouched crates, before the first move
   • Check committed mistakes and positions you could not recover from in your report

Check yourself

5 practice questions

1. The ball stands left of a crate, and the cell right of the crate is the board edge. You press right. What happens?
2. At level 9 the Moves pill reads 0 / 16. How long is the shortest route?
3. You jam a crate on your fourth move, press Restart, and then reach the goal in the shortest number of moves. How is the trial marked?

and 2 more

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Sources

1. Sokoban: origin, push-only rules, deadlocks and computational complexity (NP-hard, Fryers and Greene; PSPACE-complete, Culberson, 1997). Wikipedia
2. Goel, V., & Grafman, J. (1995). Are the frontal lobes implicated in "planning" functions? Interpreting data from the Tower of Hanoi. Neuropsychologia, 33(5), 623–642. PubMed 7637857
3. Miyake, A., Friedman, N. P., Emerson, M. J., Witzki, A. H., Howerter, A., & Wager, T. D. (2000). The unity and diversity of executive functions and their contributions to complex "frontal lobe" tasks. Cognitive Psychology, 41(1), 49–100. PubMed 10945922
4. cut-e (now Aon). smartPredict product page, archived 10 December 2019. Wayback Machine
5. Siemsen, A. (2019). smartPredict: Development insights and study results of Aon's gamified assessment series. GBA Workshop, Minneapolis. PDF
6. CadetPrep (prep site). Aon cut-e complex planning. cadetprep.academy
7. PrepInsta (prep site, candidate-reported). Capgemini game-based aptitude. prepinsta.com
8. Capgemini India. Recruitment process. capgemini.com

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