What is McKinsey Problem Solving Game (a.k.a Solve)?

The McKinsey Problem-Solving Game is a gamified test

In the McKinsey recruitment process, the Problem-Solving Game sits between the resume screening and the case interviews, serving the same purpose as the paper-based tests – ruling out the “unfit” candidates to save time and resources during the expensive case interview phase. The test is mandatory for candidates applying in all practices: General, Operations & Implementation, Research & Analytics, Digital, etc.

Note: As this is a gamified test, in this article, the two terms “game” and “test” will be used interchangeably when referring to PSG.

The new gamified test is supposedly crack-proof

Now, why did McKinsey change the test format from a paper-based test to a game? Keith McNulty, McKinsey’s Global Director of People Analytics and Measurement, put it this way:

So essentially, McKinsey is trying to create a test/game that is impossible to game (ironic, isn’t it?).

But in fact it can be broken down into bite-size pieces

With field reports from hundreds of real test takers, we have gathered enough insights to break down the McKinsey Problem-Solving Game into bite-size pieces, which are fairly consistent across candidates. Using those insights, we can derive working overall approaches to the game.

In this article, we will cover:

It is important to keep in mind that since neither Imbellus nor McKinsey publicizes the exact details of the criteria/mechanisms used in-game, the insights presented in this article – reported by our correspondents – may not reflect 100% of the in-game elements.

What is the McKinsey Problem Solving Game like?

The McKinsey Problem-Solving Game or Digital Assessment has a time limit of 60-80 minutes. The candidate is asked to solve 2 out of 5 possible mini-games. Both the final results and the process are assessed, and if the candidate is found to possess similar skills and tendencies to a McKinsey consultant, they are offered an interview.

For a more detailed guide on the technical details of the game, please check out the McKinsey PSG Starter Guide in my Prospective Candidate Starter Pack.

Time limit is 71 minutes

As of April 2021, the reported time limit for the McKinsey PSG is exactly 71 minutes, with 35 minutes recommended for the first game, and 36 minutes for the second game. Time spent on tutorials is not counted towards the limit.

Ever since the start of the PSG, there have been variations in time limit reports, however, these tend to stay between 60-80 minutes. This variation depends on the length of each mini-game.

Actual time allocation depends entirely on the candidate’s decision – however since the first game is much more predictable, we recommend playing this quickly to allow more time for the second game. With a proper approach, the first game should take only 15-20 minutes, with time for a double-check taken into account.

Candidates should also make the most out of the tutorial time – try to guess the objective of the mini-game, and think of an overall approach before beginning a mini-game. You can also use that time to make necessary preparations, such as pen and paper, or maybe a light snack to keep yourself energized.

Each candidate has to solve 2 out of 5 mini-games

As of May 2021, 5 mini-games are confirmed for the McKinsey Problem-Solving Game. The two common mini-games are Ecosystem Building and Plant Defense, the less common ones are Disease Management, Disaster Management, and Migration Management.

The first one is similar to city-building games – except with animals instead of buildings – and the second one is essentially a tower-defense game where you use defensive structure to protect the base from invaders.

Besides the Plant Defense game, three alternatives are found for the second mini-game: Disaster Management and Disease Management.

In most cases, these alternative mini-games are there for beta-testing purposes – the scores from those sessions are not likely to weight heavily in the final decision. As of May 2021, reports of the Disease and Disaster mini-games have been come extremely rare, indicating that they have been phased out; however, the Migration Management mini-game has just come into the scene, so candidates should be prepared for it.

The next part will be about how candidates are assessed – if that’s not in your interest, you can skip straight to the mini-game and strategy guide using this link.

Every keystroke and mouse movement will be assessed

Process scores, on the other hand, are dictated using data on your patterns during the whole problem-solving process – every keystroke, every click, and every mouse movement will be assessed.

The process and product scores are combined to form a profile of problem-solving skills and capabilities. And while there is no official statement from McKinsey about which candidates they select, it is likely that the more you resemble a high-performing consultant at McKinsey, the higher your chances will be.

Candidates are assessed on five core dimensions

Your problem-solving profile is drawn using the five following dimensions:

The good news is that all the skills assessed are generally not evaluated by themselves, which means training one skill will probably also drive up your assessment scores in others. This is absolutely crucial because you won’t have to go into every nitty-gritty task just to squeeze out some extra score.

Furthermore, while all capabilities must be presented for success, some metrics are considered to be more impactful than others throughout the process. From this Imbellus research paper, we could deduce that Critical Thinking, Situational Awareness, Systems Thinking are the fundamental skills that all successful candidates need to possess. Meanwhile, Decision-Making and Meta-Cognition skills mastery are the advanced skills that will transform candidates from good to great ones.

The test measure telemetry data to calculate the five dimensions

While it is hard to pinpoint exactly the telemetry data gathered since Imbellus does not fully disclose this information, one way of framing this is by each stage of the problem-solving process itself. Based on our findings from real candidates, we believe the telemetry could be assorted into the following sets, each directly influencing the key activities during the stages from identifying the problem to delivering the next-step recommendation.

Breaking down the test – Ecosystem-Building

Mini-game overview & description

In the Ecosystem Building mini-game, you have to create an ecosystem with 8 species from a list of 40. There are three key objectives: (1) the ecosystem must form a continuous food chain, and (2) there must be a calorie surplus for every pair of predator and prey (that is, the prey’s production is higher than the predator’s consumption), and (3) the ecosystem must match the terrain specifications of the chosen location.

Here’s a detailed description of data and metrics in the mini-game, and how they relate to the objectives

The candidate is free to switch between choosing location and species during the mini-game. There is also a time bar on the top of the screen.

Old reports indicate that once you’ve submitted your proposed ecosystem, you would receive a score-card in the end showing how it actually plays out. Key measurements might include calories produced and consumed, number of species and individuals alive in the end.

However, recent reports have indicated that results might not be displayed at the end. In either case, it is safe to assume that the underlying principles remain the same.

Cracking the mini-game

The biggest challenges in the Ecosystem Building mini-game are task prioritization and data processing – most test-takers report that they are overwhelmed by the amount of data given, and do not know how to approach the problem. However, the second problem can be mitigated by reading the rules very carefully, because McKinsey provide specific and detailed instructions in the tutorials.

To overcome both challenges at the same time, first we need to know the “eating rules” (i.e. how species take turns to eat) and then we can develop a 3-step approach to meet those challenges.

EATING RULES AND FEEDING OVERLAPS

In the McKinsey PSG Ecosystem mini-game, species take turns to eat and get eaten, in accordance to very specific and comprehensive rules:

1. The species with the highest Calories Provided in the food chain eats first.

2. It eats the species with the highest Calories Provided among its prey (if the eating species is a producer, you can assume it automatically bypass this step, as well as steps 3-5).

3. The eating species then “consumes” from the eaten species an amount of Calories Provided that is equal to its Calories Needed, which is at the same time substracted an amount equal to the Calories Provided taken from the eaten species.

4. If there are two “top prey” species with the same Calories Provided, the eating species will eat from each of them an amount equal to 1/2 of its Calories Needed.

5. If the Calories Needed hasn’t been reduced to 0 (i.e.: satisfied), even if the eating species has consumed all the Calories Provided of the first prey the eating species will move on to the next prey with the second-highest Calories Provided, and repeat the above steps; the prey that has been exhausted its Calories Provided will be remove permanently from the food chain and considered extinct.

6. After the first species have finished eating, the cycle repeats for the species with the second-highest Calories Provided, then the third-highest, etc. until every species has already eaten. Note: in every step where species are sorted using Calories Provided, it always uses the most recent figure (i.e. the one after consumption by a predator).

7. At the end of this process, all species should have new Calories Provided and Calories Needed, both smaller than the original figures. A species survive when its end-game Calorie Needed is equal to 0, and Calorie Provided is higher than 0.

Let’s take a look at an example – try applying the rules above before reading the explanation, and see if you get it right:

Now, here’s how this food chain is resolved:

With these rules in mind, let us go through a 3-step process to building a food chain:

Breaking down the test – Plant-Defense

Mini-game overview & description

The second mini-game of the McKinsey Problem-Solving Game – Plant-Defense – is a turn-based tower-defense game. The candidate is charged with defending a plant at the center of a grid-based map from invading pests, using obstacles and predators, for as long as possible, until the defenses are overwhelmed and the plant is destroyed.

Here’s a detailed description of the gameplay:

Cracking the mini-game

As the Plant Defense mini-game of the McKinsey Problem Solving Game is essentially a tower-defense game, the basic tactics of that game genre can be applied – namely inside-out building and kill-zones. However, as the mini-game locks you from changing placement after a number of turns, contingency planning is also necessary.

I’ll elaborate each of those tactics:

INSIDE-OUT, MULTI-LAYERED DEFENSE

In this tactic, you build multiple layers of defenders outwards from the base, assisted by terrain.

Place your resources close to the plant first. As the inner rings of the map are smaller in circumference, and paths usually converge as you advance towards the center, this helps you maximize the coverage of each resource around the plant early on. In the example below, the “inside-out” approach only takes 8 resources to protect the plant from all directions, while the “outside in” approach takes 24. With this approach, place your most powerful resources closest to the plant, and expand with the less powerful, but longer-range ones.

BIG-PICTURE MINDSET

This isn’t so much of a “tactic”, but a reminder – after 15 turns, you won’t be able to change or place more resources, so try to identify the pattern of the invaders, and quickly adapt your strategy accordingly. It will take a few initial turns to experiment which works best for each type of invader.

Use your resources prudently, create an all-round protection for the plant – lopsided defenses (i.e heavy in one direction, but weak in others) won’t last long – and lasting long is the objective of this mini-game.

Alternative mini-games – Disease & Disaster

Early reports also indicate 4 alternative mini-games as replacements for Plant Defense – called Disaster Management, Disease Management and Migration Management and Redrock Study (updated in 2022). With the limited information available, it seems these alternatives are rare, but it is best to know what their objectives are and how to deal with them.

Alternative 1: Disaster Management

In the Disaster Management mini-game of the Problem-Solving Game, the candidate is required to identify the type of natural disaster that has happened to an ecosystem, using limited given information and relocate that ecosystem to ensure/maximize its survivability.

With the two main objectives in mind, here’s how to deal with them:

Like the Ecosystem Building mini-game, you will solve this mini-game only once, unlike the Plant Defense and the next Disease Management mini-games with multiple maps.

Alternative 2: Disease Management

In the Disease Management mini-game of the Problem-Solving Game, the candidate is required to identify the infection patterns of a disease within an ecosystem and predict the next individual to be infected The game gives you 3-5 factors for the species (increasing as the game progresses), including name, age, weight, and 3 snapshots of the disease spread (Time 1, Time 2, Time 3) to help you solve the problem.

There is one main objective here only: identify the rules of infection (the second is pretty much straight forward after you know the rules) – and this is another problem-diagnosis situation. The issue tree for this mini-game should have the species factors as branches. Skim through the 3 snapshots to test each branch – once you’re sure which factor underlies and how it correlates with infection, simply choose the predicted individual.

Alternative 3: Migration Management

The Migration Management mini-game of the PSG is a turn-based puzzle game. The candidate is required to direct the migration of 50 animals. This group carries a certain amount of resources (such as water, food, etc.), often 4-5 resources, each with an amount of 10-30. Every turn, 5 animals die and 5 of each resource is consumed.

It takes 3-5 turns from start to finish for each stage Migration mini-game, and the candidates must place 15 stages in 37 minutes. The candidate must choose among different routes to drive the animals. In each stage, there are points where candidates can collect 3 additional animals or resources (1-3 for each type), and choose to multiply some of the collected resources (1x, 3x and 6x); the game tells the candidate in advance which resources/animals they will get at each point, but not the amount.

The objective is to help the animals arrive at the destination with minimal animal losses, and with specific amounts of resources.

With all of these limited insights in mind, here’s what I recommend for the strategy:

Alternative 4: Redrock Study

The Redrock Study is the latest mini-game McKinsey has just rolled out in 2022. Its format is different from other Problem-Solving Games. In Redrock Study, the candidate plays the role of a researcher with tasks following a research process. Within 25 minutes, candidates will be instructed step-by-step to move through three stages:

Overall, the game tests a combined set of skills: chart reading, percentage calculations, data interpretation. Mastering these skills individually by preparing for numerical reasoning tests can also familiarize you with questions types.

MConsultingPrep has constructed a Simulation for Redrock Study, including accompanied guidebook and mock cases to prepare yourself for the real Test. The Simulation is developed based on feedback from real test-takers in 2022. Checkout the Simulation by yourself and experience first-hand the experience of the Test.

Test-taking tips for McKinsey Problem-Solving Game

Besides the usual test-taking tips of “eat, sleep and rest properly before the test”, “tell your friends and family to avoid disturbing”, etc. there are five tips specifically applicable to the Problem-Solving Game I’ve compiled and derived from the reports of test takers:

Tip 1: Don’t think too much about criteria and telemetry measurements

You can’t know for sure which of your actions they are measuring, so don’t try so much to appear “good” before the software that it hurts your performance. One of our interviewers reported that he refrained from double-checking the species information in the Ecosystem Building mini-game for fear of appearing unsure and unplanned.

My advice is to train for yourself a methodical, analytic approach to every problem, so when you do come in for the test, you will naturally appear as such to the software. Once you’ve achieved that, you can forget about the measurements, and focus completely on problem-solving.

Tip 2: Don’t be erratic with in-game actions

While you don’t want to spend half your brain-power trying to “look good” to the software, do avoid erratic behaviors such as randomly selecting between the info panels, or swinging the mouse cursor around when brainstorming (yes, people do that – my Project Manager does the same thing when we do monthly planning for the website).

This kind of behavior might lead the software into thinking that you have unstable or unreliable qualities (again, we can never know for sure, but it’s best to try). One tip to minimize such “bad judgment” is to take your brainstorming outside of the game window, by using a paper, or a spreadsheet. 

Tip 3: Always strive for a better solution (Ecosystem Building)

Some of the interviewed test-takers seem to be under a wrong impression that “the end results do not matter as much as the process” – however, for PSG, you need good end results too. This is especially true in the Ecosystem Building, where a “right” answer with no species dying can be easily found with the right strategy.

Consulting culture is highly result-oriented, and this game/test has product scores to reflect that. Having a methodical and analytical approach is not enough – it’s no use being as such if you cannot produce good results (or, “exceptional” results, according to MBB work standards).

Tip 4: Learn to compromise (Plant Defense)

The game is designed so that in many cases, there will be shortcomings in even the best solutions, and your base will never survive. So pay attention to the time limit, and once you’re confident with a “good enough” solution, submit it. Remember, the time limit is shared by all the mini-games and its constituent stages, so spending too much time on one will eat up the necessary time for the next.

Tip 5: Prepare your hardware and Internet properly before the test

While the McKinsey PSG does not require powerful hardware, the system requirements are indeed more demanding than the usual recruitment games or tests. A decent computer is highly-advised – the smoother the experience, the more you can focus on problem-solving.

On the other hand, a fast Internet connection is a must – in fact, the faster, the better. You don’t want to be disconnected in the middle of the test – so tell other users on your network to avoid using at the same time as the test, and go somewhere with a fast and stable connection if it’s not available at your home.

How to practice for McKinsey Problem-Solving Game

Hypothesis-driven problem-solving approach

See this article: Issue Tree, MECE

You may have noticed a lot of the solutions for the mini-game involve an “issue tree” – the centerpiece of the hypothesis-driven problem-solving approach that real consultants use in real projects.

This problem-solving approach is a must for every candidate wishing to apply for consulting – so learn and try to master it by applying it into everyday problems and cases you read on business publications. Practicing case interviews also helps with PSG as well.

You can see the above articles for the important concepts of consulting problem-solving.

Mental math and fast reading skills

See this article: Consulting Math, Fast Reading

The McKinsey Problem-Solving Game – especially the 3 ecosystem-related mini-games – require good numerical and verbal aptitude to quickly absorb and analyze the huge amounts of data. Additionally, such skills are also vital to case interviews and real consulting work.

That means a crucial part of PSG practice must include math and reading practice – see the above articles for more details on how to calculate and read 300% faster.

Practice with video games

Test-takers who regularly play video games, especially strategy games, report a significant advantage from their gaming experience. This is likely due to three main factors:

I am not a fan of video games – in fact, after leaving McKinsey I founded an entertainment startup with the mission to fight the increasing popularity of video games. Yet now I have to tell you to spend a few hours each week playing them to get into McKinsey.

The question is, which games to play? Here’s a list of the games and game genres my team have found to possess many similarities with the McKinsey PSG:

City-building games

These are very similar in logic to the Ecosystem Building mini-game – you need to balance the production and consumption of buildings and communities, which usually have specific requirements for their locations.

The difference between these and the PSG is that most games are real-time and continuous, meaning you have the opportunity to watch your city develop and correct the mistakes – in the PSG you need to nail it from the start! With that said, the amount of data you need to process in these games will make the McKinsey PSG a walk in the park; the learning curve is not too high either, making these games good practice grounds.

Screenshot from Cities Skylines

Tower defense games

Tower-defense games such as Kingdom Rush are near-perfect practices for the Plant Defense mini-game of the McKinsey PSG. Our basic “kill-zone” tactic in fact comes from these games.

Again, there is a caveat when practicing with games – both Plants vs Zombies and Kingdom Rush allow you to correct your mistakes by having the invaders attack the base multiple times before you lose. Both games also feature fixed and predictable paths of invasion. In the PSG, the path of the invaders changes with your actions, and if they reach your base, you’ll lose immediately.

Grand strategy and 4X games

Grand strategy and 4X games combine the logic of system-building and tower-defense games (with Civilization being the best example), making them good practice for both games of the PSG. They also require players to manage the largest amount of data among popular game genres (sometimes multiple windows with dozens of stats each).

However, they are also the game with the steepest learning curves – so if you are not one for video games, and/or you don’t have much time before the PSG, these games are not for you. They are also less similar to the PSG on the surface, compared to the two genres above.

Screenshot from Civilization VI