Ecosystem Building simulation
Ecosystem Builder is our timed simulation of the Ecosystem Building format. Choose eight of 39 species and a location on a terrain map, then watch the eating order decide whether your ecosystem survives.
What the Ecosystem Building is
Ecosystem Building is the module most older Solve guides lead with. It has left the default lineup but still appears in some versions. You choose eight species from a catalog of 39 and a location on a terrain map whose conditions fit all eight.
The species then eat in a fixed order: the species with the most calories provided eats first, from its richest food source, and the ecosystem survives only if every species’ needs are met and none is eaten down to zero. Prep sources and two published solvers agree on these rules. The reef, mountain, kelp and desert settings change the look, not the rules; ours rotates through four settings of its own.
How our simulation runs
- An untimed briefing works through an eating order step by step.
- Catalog: 39 species in three environmental groups of 13, with filter tabs. Each card lists calories provided and needed, what it eats, what eats it, and its condition ranges.
- Map: hover a cell to read its two varying conditions, then pin a location.
- Select eight species. Check fit tests the location against all eight; survival is revealed only in the review.
- Submit before the 35-minute clock runs out.
- Review: the fit table, a step-by-step playback of the eating order, and a surviving eight-species set from the same group.
Start the simulation
Each card shows your account’s access.
Every mode, including the full sittings and the untimed warm-up drills, is on the McKinsey Solve practice page.
Ecosystem Builder walkthrough
Ecosystem Building questions
Is Ecosystem Building still part of McKinsey Solve?
It has left the default lineup, which is now the Redrock Study and Sea Wolf, but candidates and career services report that it still appears in some versions. Your invitation and its untimed tutorials show which modules you will sit.
How long is Ecosystem Building?
Candidates report about 35 minutes. Ecosystem Builder runs on a 35-minute clock after an untimed briefing.
What is free?
Your first Ecosystem Builder attempt is free with an account, and the walkthrough on this page needs no account. A McKinsey Solve pass covers replays of every module simulation and the 65-, 85- and 95-minute full sittings, and saved reviews stay free.
What does the review show?
Whether your location fits each of the eight species, then the eating order played back step by step: who ate whom, how many calories moved and which species ran short. It ends with a surviving set from the same group, so you can compare it with yours.
Game Assessment Prep is independent and is not affiliated with or endorsed by McKinsey & Company. Solve, Ecosystem Building and McKinsey’s other module names are referenced to explain the format; our content and scoring are original. No actual assessment questions or proprietary interface assets are reproduced.