Imbellus Game: The McKinsey Solve Game Explained (2026)

Searched for the Imbellus game and found old threads about food chains, plants, and invaders? 🏝️

It makes sense that you feel lost, because you are trying to get ready for a test while reading advice written for a different one.

Imbellus is the old name of McKinsey’s online assessment, and many pages that use it describe games McKinsey no longer uses.

So what is the Imbellus game today, which games will you really play, and how should you prepare?

Well, that’s exactly why I wrote this article. I will explain where the name comes from, how to spot old advice, what you will play in 2026, and a simple plan to get ready.

Let’s dive in!

What Is the Imbellus Game?

The Imbellus game is the online, game-based test McKinsey uses to screen candidates. It usually comes after you submit your application and before any interview, and you take it at home on your own computer.

You don’t answer questions about business. You play short games set in nature, such as islands and oceans, and McKinsey says you need no business knowledge and no gaming experience.

One Test, Many Names

The name you see depends on when a page was written. These names all mean the same test:

• Imbellus game or Imbellus test: the old name, taken from the start-up that helped build it.
• McKinsey Problem Solving Game (PSG): the name many candidates still use.
• McKinsey Digital Assessment: another name you will see in guides and on McKinsey’s website.
• McKinsey Solve: today’s official name.

The one different name is the PST. The McKinsey Problem Solving Test (PST) was the older pen-and-paper, multiple-choice test that this game replaced.

Where the Imbellus Game Came From

Imbellus was a US start-up, founded in 2015, that used games to see how people think. McKinsey was its first client, because it wanted to measure how people think rather than what they know.

The two started working together in 2016 and ran a pilot in London in November 2017. The game then reached more offices, an online version was ready in 2019, and it was later renamed Solve.

In late 2020, Roblox, the video game company, bought Imbellus’s intellectual property, and the founder moved there. McKinsey says it acquired Imbellus too, and its own game-based lab now builds these games. So you will not play on Roblox: McKinsey runs the test itself.

What the Game Measures

The game is built around five skills: critical thinking, decision-making, metacognition (noticing when your approach is not working), situational awareness, and systems thinking.

Numbers and situations tend to change from one candidate to the next, so copying someone else’s answers will not work. McKinsey says Solve goes to around 300,000 early-career candidates per year, so you are far from alone.

Who Has to Play It?

Based on candidate reports, nearly everyone applying for a consulting role at McKinsey plays it. On forums, some experienced hires say they skipped it and others say they had to play, so ask your recruiter if you are not sure.

This is only McKinsey’s test. Other MBB firms, such as BCG, use their own online tests.

The Old Imbellus Games and the Current Games

An old thread only helps if you know which game it is talking about.

The Old Games You Can Skip

McKinsey has used eight games in total since the assessment started. Five of them are no longer used:

• Ecosystem Building: you picked 8 species out of 39 to build a food chain, matching the calories each animal needs with the calories its food provides. McKinsey phased it out in 2025.
• Plant Defense: you protected a plant from invaders with defenders and terrain, turn by turn. Redrock replaced it in February 2023.
• Disaster Management: you identified a natural disaster and moved animals to safety.
• Disease Management: you predicted which animals a disease would reach next.
• Migration Management: you led animals across maps while managing resources.

Here’s a quick test for any old advice. If it talks about eating rules, top predators, calories, or “15 turns”, it is about Ecosystem or Plant Defense, so you can skip it. The same goes for a 110-minute test.

My McKinsey Solve games guide covers every old and current game.

The Games You Will Really Play

Three versions of the test have been used in recent months. The time written in your invitation email tells you which one you have:

• 65 minutes: Redrock and Sea Wolf.
• 85 minutes: Redrock, Sea Wolf, and the old 20-minute Sustainable Futures Lab.
• 95 minutes: Redrock, Sea Wolf, and the new 30-minute Sustainable Futures Lab.

We have not received recent reports of the first two being used, and the 95-minute version is likely the main one now. That being said, always refer to your invitation email.

Redrock, Sea Wolf and Sustainable Futures Lab are the standard games in the 95-minute version, played in that order. Each game has its own timer and starts with a short tutorial that is not timed.

Redrock (35 Minutes)

You are a researcher studying animals on an island. It is the game with the most math: mostly percentages, ratios, and averages, with a calculator inside the game.

Part 1 is the Study. You save useful data in a Research Journal (Investigation), answer usually 3 or 4 math questions (Analysis), then fill in a short report and pick a chart to display your data (Report). Part 2 is 6 short mini-cases.

You cannot go back from the Cases to the Study, or back to an earlier Analysis question.

Sea Wolf (30 Minutes)

This game is also called Ocean Cleanup or Ocean Treatment. At each of the 3 polluted ocean sites, your goal is a final team of 3 microbes that fits the site’s rules.

The average of each of the 3 attributes must sit inside the site’s range. At least one microbe should have the desired trait, and no microbe can have the undesired trait.

Each site starts at 100% and has 5 checks worth 20% each. Some sites cannot reach 100% at all, so the best may be 80% or 60%.

Sustainable Futures Lab (30 Minutes)

This is the newest game, and it has no math: it tests your judgment. You take on a project management role over 3 simulated days, after first ranking 4 questions.

Each day has the same four stages:

• Explore: you gather information with 2–3 requests a day.
• Assign: you decide who works at each workstation.
• Support: you help a team member, choosing from 2 to 4 answer options.
• Reflect: you rate how each person is feeling.

Everything is click-based (you rank, drag, or choose from options), and the clock never pauses.

How McKinsey Scores the Imbellus Game (and What Happens Next)

Two Scores, One Result

McKinsey claims that there are two scores. Your product score is about your results: your answers, your final microbes, your chart. Your process score is about how you got there, because the game records your clicks and choices.

Think of it like a math teacher who marks your working as well as your final answer. Calm, organized habits matter, not only the end result.

McKinsey does not publish exactly how the scores are calculated, or a pass mark. If you ask HR, you can get your result as a decile from 1 to 10, and I suggest aiming for decile 8 or higher. There is no official pass rate, but unofficial estimates say about 20 to 30% of candidates pass.

Can You Still Pass After a Bad Run?

Forums are full of this question, often from candidates who ran out of time. McKinsey says your result is considered together with the rest of your application, so your CV still counts.

Coaches on those forums also report candidates who did not finish a game and still reached interviews. Nobody outside McKinsey knows exactly why one candidate passes and another does not, so don’t try to work it out from one mistake.

Results usually come within a few weeks, sometimes within days.

What Happens After You Pass

If you pass, you will usually be invited to a case interview, together with a personal experience interview (PEI). Those interviews decide whether you get a role at McKinsey, so start that preparation early.

How to Prepare for the Imbellus Game

McKinsey says no preparation is needed. We suggest you prepare anyway, because the format is new to almost everyone and the time pressure is real.

My line is quality over quantity: a few careful practice runs, each one reviewed, are worth more than 20 rushed ones.

Be extra careful with material that still uses the old Imbellus name. Before you trust any practice tool, check that it matches the version in your invitation email, and that it explains what a good move is and why. That is why we built playable simulations of all three games, including the new 30-minute Sustainable Futures Lab.

A Simple One-Week Plan

Candidates usually get 1 week after the invitation to take the test, so plan around your deadline from day one:

1. Learn how each current game works. Most mistakes come from not knowing the rules, not from hard math.
2. Brush up on basic math. Percentages, averages, and ratios cover almost all of Redrock. You can practice with our free Redrock case course here.
3. Play each game once without a timer, then with the real time limit, and write down your biggest mistake after each run.
4. Plan how you manage time. Aim for about 2 minutes per Redrock case and about 10 minutes per Sea Wolf site.
5. Rest a few hours before. A fresh mind is worth more than one extra run.

For a longer plan, see my guide on how to prepare for McKinsey Solve.

What the Rules Say About Tools

McKinsey’s rules say you may not use applications, websites, AI tools, or pre-prepared notes, or take screenshots, and you must play alone. It also says it may ask some candidates, at random, to explain their reasoning or do an extra task in person.

We still suggest an Excel solver, as Excel is not ruled out as an option in the instructions and it saves a lot of time on the hardest step. In Sea Wolf, that step is picking the final 3 microbes, and we have our own solver for exactly that step, so practice with it before the real test.

Never use AI tools during the test, as they are clearly stated as not allowed. Also, the only time to take a screenshot is when something breaks, so you can show McKinsey’s support what happened.

Common Mistakes and Test-Day Tips

• Preparing for the wrong games. Old advice on Ecosystem or Plant Defense will not help you.
• Collecting every piece of data in Redrock. Much of it is only there to distract you, so start from the research goal.
• Mixing up percent and percentage points in the Redrock math.
• Spending too long on the first Sea Wolf site. Move on so you reach all three sites.
• Skipping the tech check. You need a PC or Mac, not a phone or tablet, so run the check early. A mouse is optional but makes dragging easier.
• Waiting to report a problem. If something breaks, contact McKinsey’s support right away.

Frequently Asked Questions About the Imbellus Game