McKinsey Problem Solving Game (Solve) Explained - with Footage

McKinsey Problem Solving Game (PSG), Imbellus Game, Digital Assessment, or - as of late - McKinsey SOLVE - all of these terms refer to the same pre-interview screening test employed by McKinsey, starting from 2020 as a replacement for the old McKinsey PST.

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Timestamps:

0:00 Intro
0:52 Part 1: What is the PSG?
3:08 Part 2: The mini-games of the PSG
4:39 Part 2.1: Mini-game #1 - Ecosystem Building
12:14 Part 2.2: Mini-game #2 - Plant Defense
19:20 Part 3: Q&A
23:22 Outro
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McKinsey Solve Simulation (fully-interactive mock tests, with guidebook; up-to-date for 2024).

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OTHER RESOURCES

Overview of the 2022 McKinsey Solve (up-to-date for 2024 Ecosystem Building), highly recommended:
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[leandeer]

Just completed the PSG test, and the tutorial was great!

For the ecosystem task, it took a bit longer than i anticipated and was in fact much harder than the plant defense. I used 40min and managed to keep the ecosystem alive. Some pointers for all you out there reading the comments to gain a better understanding of the test.

1. Prioritize the animals with the highest calories provided and lowest calories needed.
2. All the animals and producers are divided into three categories based on the terrain variables. Keep an eye out for the variables that change in between species, those are the ones you should focus on. For me, that was temperature and elevation/depth.
3. Always build your ecosystem based on the steps above, but do not forget to sort in which animals get eaten by each other. If you have a producer that is not eaten by anyone, it simply does not add value to the ecosystem, and that's a negative.
4. The Imbellus game tracks everything you do, so show what you are thinking to the game, and show YOUR process to find the answer. It is nice to calculate on the side, but show them that you screen for information. If you do everything on pen and paper, how can they tell if your process was good?
5. Write a full overview in excel of all the producers, what they get eaten by, and calories in vs calories out. This makes it easier to change the ecosystem if you do something wrong the first time.

For the plant defense task, I got 22-25-34, but think I could have done better. I did not use much terrain, only defenders like animals. Focus on deploying then in NSEW of the plant you defend. Read what the defender's abilities are, important. Show the game that you read the guidebooks, and screen for all needed info, as I think this is important in their valuation as well. Place defenders in every direction, plan ahead and see patterns.

Hope this is of some assistance to everyone. Go get it!

[soulsynth]

Thank you so much for the tutorial! I took the test a few days after this video was uploaded and have been extended an offer to join the firm as a Business Analyst, when I graduate next year :)

[kalika]

Thank you for this video - I took the PSG today and this was one of the only useful resources I came across in terms of "preparing" for the PSG. I watched your video 2-3 times and used the note taking strategy, and also the plant defense strategy.

[allround]

Hi i took the test today and did poorly on the ecosystem, there are topics that aren't covered much in the video .
1.) you need to concentrate more in the location where the species grows, only a few species grows on the correct location.
After building the food chain, i found out that different species grows on different location.
2.) don't waste more time on selecting the species, use time wisely.

[maryamalawadhi]

Just finished the game and I don't know how to thank you enough, I wouldn't have ben able to understand the first game without this video!! and the second game is easier than it seems and I actually had fun playing it! GOOD LUCK EVERYONE and thank you so much for this video.

I think this is a MUST watch video for anyone taking the test.

[adilbekrustemov]

This is the most usefull PSG information I have ever heard. Thank you!

[susu]

Just finished my PSG an hour ago. Thank you much for this great tutorial!!! By following all the tips in this video and on the website, it's really easy to crack PSG. Especially for the ecosystem game, it is not as hard as I thought. By following the tips, it is obvious to know which species group to choose without a second thought. For the plant defense game, the pattern is predictable and the strategy is really straightforward, so easy one I would say. I made 3 maps over 35 moves in the end.

* Result updated: HR reached out to me after 1 hr and said I aced the PSG with a really impressive score. It is all thanks to this video. Again, thank you very

[peteryu]

I think the only thing you care to prepare for would be familiarity with the scenarios and some general rules. Like many others are saying you can't really prepare or improve a certain measured competency because it's SO nuanced of a game from one candidate to the next.

I just took the PSG (06/23/22) and out of everything on the internet (unpaid/free) this was the most useful video!!! I believe I passed the test and would recommend just sticking with this video!! Good luck!

[zenonever]

Thanks for this guide, indeed the best prep for this game existent, I really appreciate your work. As for the tips:
In ecosystem building remember that not necessarily the producers with highest callories are the best - sometimes one of the most sufficient is eaten by no animal - therefore worthless. Having chosen producers focus on what they are eaten by and draw a tree starting with most calories provided in the layer. Don't spend too much time on following the data - just elevation/depth should be sufficient and then follow calories only. As from what I observed, the game can be solved with more than one ecosystem - even in one category of producers. Most important is not to overlook any species - even if it looks useless at first glance (very low cal provided and high cal needed) it might be crucial later on, especially on the first level above producers.
Regarding the second game - Invasive species - observe pattern the animals follow - I think the best is to secure straight lines like North/South and West/East from the plant, I wasted too much resources making full circle around. When you get new defender at the end - use it, most likely it will be most powerfull one. Don't build your defense too close the plant (that's what I did). If area covered by predators overlaps with plant then you waste precious square of predator power. Survived 32, ~25, 33 rounds, passed :)

[AA-idhl]

Just completed my PSG. Wanted to echo everyone's sentiment of how helpful this video is!

[divyabajaj]

Thank you so much for this video. It was extremely helpful and informative, helped me quite a lot for my actual PSG.

[ZackSav]

This is the most helpful prep breakdown by far! I just completed mine earlier today, and having that total breakdown system of how to do the calories was by far the most helpful learning tool ever. I was able to achieve all of my species to successfully live, and the tips for the second game help. I made it to round 32 on my first round ever.

[tarikattia]

Just completed the assessment (Ecosystem and invasion). Thanks a bunch for the video AND the simulation package. Just following the video would not have been enough for me and investing in the package was definitely worth it. I recommend practicing and getting into a routine. Again Thanks!

[mureithiesther]

I'm just from doing the test! Thanks so much for this tutorial.
The most useful intel I got from the tutorial is:
1. Using a pen and paper instead of excel. Personally, I write faster.
2. Bottom up strategy. Producers first.
3. There's a lot of noice in the data. Find the most relevant, using two data points.
4. Don't obsess over calorie calculation. Ensure you have the 8 species first, create a rough pyramid structure with the template shown in this video and estimate the calories. If you have more than 10 minutes left after selecting the location, then you can do the calculations.
I've found it very helpful. Most importantly, the comments people left are even more helpful since it provided more recent info for me. I didn't bother with the Plant defence section since I was sure they'd bring the RedRock study as people stated in the comment section. The ecosystem builder section is definitely easier than the redrock bit. I'd advise you polish up on percentage calculation and probability. I guess you shouldn't be worried about completing the study section, I haven't come across someone who has. I think it's more useful to do the ones that you do correctly.

[arunkumarkv]

The best one in the YouTube! If you are here, you are sorted. Good luck.

[xNakiru]

I did the PSG test yesterday (got Ecosystem and Red Rock Study games, separate time clocks) and wanted to share my experience since the other comments helped me quite a bit. My preparation basicially began around 4 hours before the exam and mainly consisted of watching this video twice and look through the comments. I saw preparation tools/guides etc. online particularly for the PSG which sold for over 200 USD which in my opinion are not necessary and rather a waste of money but hey, if money isn't a problem it certainly wouldn't affect your performance negatively. Here are some details regarding the games:

1. Ecosystem (coral reef): As often suggested in this comment section I took the bottom-up approach and started finding the group of producers with the same depth and temperature requirements which provided the most calories. Then with a prepared excel sheet on a separate laptop I listed all the species fitting the required conditions my producers needed including the most important details. From there on I just prioritized the species with higher cal provided/lower cal needed and made sure that they eat/get eaten by the other producers/species. Though it can become pretty messy with all the data it generally is quite straightforward and after around 30min I had a 3-3-1-1 working ecosystem and got the three green checkmarks after completing it. I highly recommend using either a pen and paper or excel sheet to gather all the compatible species and their most important info. Also be aware that certain species might have similar names (e.g. "common angelfish" and "dark blue angelfish") so don't get them messed up.

2. Red Rock Study: I didn't prepare at all for the Red Rock Study and pretty much had no idea what it is about. The good news is that you don't really need to prepare for it. I had two parts with the first one being a study you conduct where you will be provided with some information and questions mainly requiring small calculations and a final report summarizing your findings. You will be provided with a "Journal" which you can use to save certain information with drag and drop from the report provided to answer the questions. Make sure to get all the information before going into the final report because you won't be able to go back. This is not the case for the questions, there you can go back anytime. The second part was 6 small cases/questions unrelated to the study where you just have to conduct some basic calculations. Generally it's rather simple and I would argue that if you are familiar with a bit of math there's no need to prepare for the Red Rock Study.

I think I did pretty well throughout the whole assessment but I'll let you know as soon as I hear back from recruitment.

Let me know if you have any questions, good luck! :)

[nurse.carmela]

I've just finished the PSG. It was very challenging, but I've got to say that I prepared the test like A LOT. I did an excel sheet and diagrams and printed them out to fill them in during the test.
My approach: On my excel sheet, first I wrote down first the 9 producers, with depth, temperature, cal needed, cal provided and eaten by. It takes time, but it's an excellent way to see data clearly. In the end, you'll have three groups with three producers each. I chose one of those groups, based on the highest cal provided. After that is kinda easy, cause you just have to rule out the fishes that don't match the depth and temperature criteria. I stuck in front of me a sheet that had the most important rules: 1) who eats first (more cal provided) 2), what fishes get eaten first (the one with more cal provided), 3)and lastly the species that survive are the one that end up with cal needed at 0 and cal provided > 1. You can't forget those.
Another tip: use 2 laptops (or screens) to solve the game. On one screen the PSG running, on the other screen your excel sheet.
The second mini-games were kinda strange, I couldn't count the number of moves that took to get the plant eaten, but I don't think I nailed it at all.
Good luck everyone, and thanks for the little tips and comments I read on this video.
After 3 days I got an email saying I've passed the test!! yeeeiiii
Chao!

[Uyinon]

Welp I took my test today! Your tips helped for the ecosystem part, thank you!
.
I took my test today. Fingers crossed whilst waiting for my result / feedback!

[sulaimanmaharshiyam]

Thank you for this video sharing, my past week are busy seeking video references regarding this game and I think this is the best video among others on Youtube because it shows an example which almost 90% similar to the actual game.

I just took the test a few hours ago, and I got my time consumed by the ecosystem test for more than 30 minutes because I messed up with the framework upon solving the tests whether top down or bottom up. I just realized in the middle of the game, I can go by selecting a certain environment which you will go to, go by top down method, filter the animals based on top predator's prey, and so on until you can map all the ecosystem from top predator to the producers. as a little tip, don't be panic if you spend the time in first game more than the suggestion, just focus on your tasks and complete it. Sadly I got failed because one of the animals do not have enough calories, even though I could complete the second game.

Hope you guys will succeed in these tests!

[zeeworlddotcom]

This is the best tutorial ever!!! Thank you so much for doing this! Just completed Solve/PSG and it was really great. I completed the ecosystem task in 26 minutes and still had 16 minutes left after I was done with the entire assessment.

Tips for future test takers:
1. Watch the video as many times as possible.
2. Read the comments, I repeat read the comments. It will help in forming a strategy to help you complete the task in time.
3. Don't stress. The video said it would be overwhelming at first and it's true. Make sure you do something relaxing before taking the test.
4. Overestimate the diffcult level of this assessment, it will help you prepare extensively.
5. Follow the advice of having a scratch paper or excel sheet in hand(I personally prefer the scratch paper). That is literally your brain.
6.Finally, if you are building from bottom up, pick the producers with high calories provided and low calories needed.

Again, thank you so much for this!!!