McKinsey Solve/PSG: 16 Proven, Non-Nonsense Tips

Being the replacement for the paper-based McKinsey Problem-Solving Test, the McKinsey PSG is a one-of-a-kind recruitment test. Designed by Imbellus for McKinsey, the PSG is a gamified test that assesses candidates on five cognitive skills. Knowing how the game works is only the first step, you will need to know a lot more if you want to pass this notoriously unique test.

A brief recap of the McKinsey PSG

Before we get down to brass tacks, we will need a short revision of the game. Of course, if you don’t know much about the test already, you can check out a full breakdown of the PSG, where you will learn what the game does, what it tests, and the best strategies for passing.

The game tests candidates’ five cognitive skills

The PSG, meaning “Problem-Solving Game”, or just “Solve” as it is called recently, is designed to assess a candidate based on five dimensions:

• Critical thinking: The ability to form logical arguments and judgments from a broad set of facts.

• Decision-making: The ability to devise the best course of action from many options

• Meta-cognition: The ability to synthesize and process a massive load of information (e.g., note-taking, hypothesis testing)

• Situational awareness: The ability to make connections between various factors and to deduce outcomes of presented variables

• Systematic thinking: The ability to understand cause and effect relationships involving several factors and feedback loops (e.g., anticipating several orders of consequences.

While all these skills are interconnected and improving one equals the betterment of others, some skills receive more attention than others. This Imbellus research paper shows that critical thinking, situational awareness, and systems thinking are considered fundamental skills for successful candidates. The other two are more advanced skills that transform candidates from good to great.

Each candidate has 70 minutes to solve two mini-games

There are six confirmed mini-games for the McKinsey PSG:

• Ecosystem Building: Creating an ecosystem in a predetermined terrain with many parameters and variables to take into account

• Redrock Study Task: Conduct research by investigating, collecting and analyzing a massive amount of data

• Plant Defense: Deploying predators to protect a rare plant from a variety of animals 

• Disaster Management: Identify the natural disaster occurring to an ecosystem and take measures to ensure the safety of the said ecosystem

• Disease Management: Identify and analyze a disease’s infection pattern, then predict its spread to protect the ecosystem 

• Migration Management: Directing a group of animals from one point to another in a way that saves the most resources and animals

Out of these six mini-games, candidates will only have to play two. The first one is always Ecosystem Building. The second one can be any of the remaining five. Redrock Study Task is the most frequently encountered recently, gradually replacing the Plant Defense; while the other three mini-games are mostly there for beta-testing purposes. 

Watch the below video about Redrock Study Task to learn this new game!

As of May 2023, Disease Management, Disaster Management, and Migration Management have been reported to be extremely rarely seen, indicating that they are now out of the picture. 

Excluding the time for reading instructions, the total allowed time for completing both games is 70 minutes.

Time to get down to the tips for passing this gamified test, shall we?

Tip 1: Try not to spend more than 30 minutes on one mini-game

Taking the PSG can be stressful with the countdown clock right in front of your face. That is why you cannot be spontaneous during the test. Have a plan, and stick to it!

As mentioned before, the total time allowed for the PSG is 70 minutes, which means you would have about 35 minutes for each mini-game. Therefore, our advice is to practice rigorously to finish each mini-game in under 30 minutes. This is very important, as many underperform in the real test compared to their training performance. Besides, having some spare time means you can double-check your answers. 

Tip 2: During the test, check the clock every now and then

The test can be immersive in a negative way. You can get way too absorbed into the mini-games and completely lose track of time and won’t have enough time left for the second mini-game, or worse, to submit your results.

So, do check the clock from time to time to make sure you are still sticking to the plan. 

Tip 3: Brush up your mental math skills

The PSG requires you to be quick on your feet, and your mental math skills will come in extremely handy when time is running out.

Let’s take the Ecosystem Building mini-game for example – it requires you to do a lot of calculations regarding the calories the animals provide and need. You will need to find out the discrepancies among the animals to arrange a food chain and ensure that all of them stay alive in the end.

Another typical example is the Plant Defense game. Each invader has a certain population – the PSG equivalent of “health points”, and each defender does a certain amount of damage in a turn. You need to add up, extract, and compare the difference between the damage done and the remaining population to see if your defenders can exterminate all the invaders.

If you are unsure about your mental math skills, practice with my Comprehensive Math Drills package. Not only is there web-based software that you can practice calculations with, but you will also get more in-depth consulting-related math. If you pass the PSG round, the program will come in handy even more for the case interview. 

Tip 4: Make sure your setup is adequate

As we all know, the PSG is a series of online 3D games, which means your computer and Internet will be put under a lot of pressure. If your setup gives up on your mid-test, you are unlikely to get a second chance and you can say goodbye to your McKinsey dream for now, sadly.

Just recently, one of my clients actually did get disqualified from this round due to technical problems. No one wants that to happen, so you should be careful and make sure your setup is up to the task.

To help you find out if your computer can handle the workload, I have devised an entire list of system requirements for the PSG. Make sure to read it carefully and do the test with the best gears possible. 

Tip 5: Ditch the spreadsheets. Stick with pen and paper

Although these items have been mentioned in the previous section, I should remind you once again that they will be the best form of note-taking for the PSG.

Firstly, if you use spreadsheets, you will need to switch tabs/windows frequently. This may reduce your ability to concentrate and make double-checks harder. In the worst cases, you might accidentally close one of the windows.

Secondly, this multi-tasking might drastically reduce the performance of your computer, which apparently hinders your test performance. This mostly happens on really old computers trying to run the “latest and greatest” versions of browsers and office suites (say, trying to run the PSG along with Office 360 on a 4GB-RAM laptop – I happen to know candidates who did this and failed the test because of the lag induced in the Plant Defense mini-game).

Last but not least, drafting with pen and paper is generally faster and a lot more flexible. You can easily draw maps, charts, and issue trees for better visualization. You can also scrap everything you have written and start anew a lot faster, which is especially effective when dealing with a massive amount of information that the PSG bombards you with.

That said, if you ARE comfortable with using spreadsheets AND your computer can afford to run both simultaneously, OR you have two screens side-by-side, suit yourself! McKinsey allows you to use spreadsheets, and our surveys indicate that you can pass the test either way. 

Tip 6: Use the tutorial to learn about the game mechanics

Spend 10-15 minutes on each tutorial – or until you are absolutely sure about how everything works. As mentioned above, the mini-games contain a lot of information to process, and if you do not have a good grasp of what the variables mean, or what to do with the given information, you are essentially failing.

Of course, you should familiarize yourself with all the games’ instructions before you take the PSG. You can do that by practicing with my simulation, or simply reading the full breakdown of the minigames. The simulation offers a hands-on experience with the two popular games, while the written guide offers insight into all six.

But even if you have memorized everything I wrote, you should not skim too fast on the actual test’s instructions. My information, as carefully researched as it is, can still leave out something due to a new unannounced update from McKinsey.

Tip 7: Learn to filter noise from relevant data

The very moment you start reading the tutorial, be sure to take notes of which information to prioritize. I advise categorizing data by main tasks, important variables, and potentially misleading information.

Create a table and start arranging variables into each category. With a note matrix like that, you are more likely to identify which information can be helpful. For example, in the Ecosystem Building minigame, the most important variables are the calories provided and required by animals, and the conditions mentioned in each species card.

Do not, at any cost, attempt to make mental notes. Mental math is necessary to avoid wasting time, but not writing down information will do the opposite. Not only is it more likely for you to leave out minor but important details, but you can also panic and fail to remember something. Without properly written notes, you might need to go through all the data again, wasting precious time.

Tip 8: Be comfortable with incomplete information

You might not have all the necessary data to make a perfectly informed decision, and that is okay. Some of the PSG mini-games deliberately create these situations to see how well a candidate may perform in similar, real-life settings. 

Examples are the Plant Defense mini-game (you don’t know when and where the invaders are coming from), or the Migration mini-game (you don’t know how many resources or animals can be picked up at any given checkpoint).

This tip is aimed at preparing your mindset before taking the test. Although no one wants the situation to come to that, sometimes, you will need to make guesses. Of course, you should consider all possible possibilities for your hypotheses, but should anything be missing, do not panic.

Tip 9: Test your hypotheses on paper before making decisions

After you have composed enough information and chosen the right combination of animals or paths, write them all out once again, and see if there are any inconsistencies or holes in your logic. Except for maybe Plant Defense, all of the other minigames will entail a lot of hypotheses and possible routes.

When testing your hypotheses, use your calculator to avoid making unwanted mistakes.

Tip 10: Prioritize species with high calories provided and low calories needed (Ecosystem Building)

The whole point of the Ecosystem Building game is to build one that is “sustainable”. To do that, you will need to match the living conditions for the species with those of the chosen location and make sure every species has enough food to survive.

The first part is easy. You can do it before, or after building the food chain (ideally AFTER building the food chain). It literally takes seconds, and it is about as simple as primary school math.

The second part is the hard one. McKinsey will give you a set of eating rules (detailed in the main article here) to help you figure out how species will take turns to eat. Again, more insights are given in the main article, but the key takeaway is that if every species in your food chain eats less and produces more, the whole food chain is more likely to sustain itself.

Tip 11: Use keyboard numpad (Redrock Study Task)

Redrock Study Task requires the use of the on-screen calculator to input the results of your calculation. You can speed up this process by using the keyboard numpad. Since the numpad is derived from a calculator, it provides calculator-style efficiency for entering numbers.

You can also use the number keys if you prefer or do not have a numpad. No matter what, it is much faster than clicking on each character of the on-screen calculator.

You can also try separating a long math expression into smaller segments for easier calculation. This might take a little bit more time, but because the calculation is shorter, it would be harder to make mistakes, and even so it would be easier to check and fix. 

MConsultingPrep’s Redrock on-screen Calculator (Left) 
vs Numeric Keypad (Right - photo taken by Wassily Frese)

We recommend you to watch this guide video then you will know how to use the Redrock on-screen caculator.

Tip 12: Keep your Research Journal organized (Redrock)

Another tip for Redrock is to have a clean and organized Research Journal. This will help a candidate navigate faster through all the collected data, which might save a lot of time in a time-stressed test. 

To have a clean and organized Journal, each data point should be labeled, and related data points should be set close to each other to ensure coherence. Those labels and organization will help you remember what’s what. 

While this may cause some loss of time, it is worth remembering that your memory might fail you sometimes, and when that happens, it takes a lot more time to go back and check the data.

Furthermore, we also suspect that McKinsey might evaluate how you collect and store data on the Journal to calculate the final score. If time is not your concern, then maybe you should be concerned about this. 

Tip 13: Protect inside-out (Plant Defense)

When you really think about it, Plant Defense is a game of probability. The map is a grid system made up of small squares, with all elements taking up just one small square. The plant is located on the square in the middle of the map, meaning invaders will always go through at least one of the 8 surrounding squares to reach the plant in the center.

8 squares are easier to cover than, say, 24 squares in the “outside in” approach.

And that is why you need to plan your defenses from the inside out. Start with the circle around the plant and expand.

Tip 14: Draw an Issue Tree (Disease/Disaster Management)

These two mini-games are the closest to a case interview, in the sense that you need to identify and solve a problem. Here, you will need to develop hypotheses to determine the disaster's infection or spreading pattern. And how do you work around hypotheses? With issue trees.

If you are unfamiliar with hypothesizing, feel free to check out the video below. It will not only help you with the PSG but also with your prospects as a consultant in general.

For the Disaster Management game, you should first skim through the data bottom-up to form a hypothesis. After that, draw an issue tree with each in-game disaster as a branch. You can then test your hypothesis with all the data possible – take into account variables like wind speed, temperature, etc.

For the Disease Management game, you will be identifying the infection pattern in an ecosystem. Thus, each branch of your issue tree should be a species factor. You will be given three snapshots (or phases) of the disease spread, which you should use to determine where it is spreading next. When your hypothesis has been tested, you should be able to identify the next animals to be infected.

Tip 15: Prioritize the route with the highest number of animals (Migration Management)

Should you stumble upon this game, your task will be to direct the migration of 50 animals, with 5 of which dying every turn. The game mechanics allow you to go to points where you are provided with resources to keep the animals alive, as well as more animals (you cannot know how many you will get, however).

With the rules in mind, the strategy for the game is really simple: Prioritize the path that gives you the most animals, with just enough resources to not let them die out.

Also, this minigame is where your mental math skills will come in handy. You will need to calculate in advance the end results of each route – how many resources and animals you get at each collection point. I highly recommend drawing a matrix with columns being resources and animals, and rows being the routes. The matrix will allow you to eliminate incompatible routes. 

Tip 16: Familiarize yourself with the minigames by practicing with a mock test

Everybody knows that you should practice before taking any test. The problem is that the McKinsey PSG is not a standardized or widely known test, but rather very niched and used by one company, for one purpose only. In addition to that, the PSG is a game with random variables, so how can you prepare for it?

Good news, because I have just the right tool for you! Our unique PSG simulation is the closest thing to the actual test. The simulation features the two most frequently seen minigames – Ecosystem Building and Redrock – including: 

• Over 150 species for Ecosystem Building, with practice mode and real-test mode, and randomized algorithms to make sure the test is as challenging as the real one

• Five large cases and fifty additional mini-cases for Redrock, combining into five training scenarios, with more coming soon.