Due to its unpredictable nature, the Plant Defense mini-game in McKinsey Solve can cause a lot of trouble for the test-takers. According to recent McKinsey candidates, you can easily get defeated very quickly without careful calculation and a proper strategy.
I have collected different insights and tips from the former participants of the Plant Defense Game and gathered them in this post. Let’s check it out now!
Plant Defense Game - McKinsey PSG overview
What is Plant Defense Game?
PSG Plant Defense Game is a turn-based defense game. Your task is to use defenders and predators to repel invasive pests as long as possible from the central plant in a grid-based map. When the barriers are breached, and the plant is destroyed, the game is ended.
There are two phases in the game:
- The first phase (from 1st to 15th turn): you will be able to arrange your defenders and predators in 3 waves of 5 turns. In 3-5 turns, the invaders start traveling from the map’s border.
- The second phase (after the 15th turn): This phase occurs following the 15th turn. All invaders from the previous stage will continue to assault. Your defense arrangement is fixed and unchangeable. – you can not relocate, add or remove your defenders. Invaders will rise and move closer to the base indefinitely until the central plant is destroyed.
Five basic game rules of Plant Defense
Rule 1. Your score is based on how many turns your plant can survive until the invaderé destroy it.
Rule 2. You are permitted to pick and put five resources at the start of each wave. The two types of resources are Defenders (such as Coyote, Snake, Falcon, etc., which kill the Invaders) and Terrains (comprised of Cliff, Forest, and Rocky, which slow down or block the invaders).
Rule 3. Rules of Defender and Terrain
- Each will be assigned to one turn of the current wave. After each round, the Defender/Terrain for that turn is active and locked, meaning you cannot modify or remove its location. You can change the following moves to suit the situation.
- The single exception is the Cliff, which activates immediately after placing.
- Each Defender has a range/territory; if an invader enters that range/territory, the Defender damages them, diminishing their population.
- Each defender type has a different affecting range, but generally, the more powerful the Defender, the shorter the range.
- Each Terrain and Defender will occupy one square.
- You cannot place Defender on top of an existing Defender
- If a Terrain is placed on top of an existing Terrain, it will replace the existing Terrain.
- Defenders and Terrains form mutually compatible pairs to exist on the same square.
Rule 4. Rules of the Invaders
- Invaders will appear from the map borders every 3-5 turns in stacks of 100-200 populations each.
- They move one step closer to your plant with each turn.
- The population of the stacks increases gradually.
- Each Invader stack is accompanied by a path indicator – a long yellow arrow showing its direction.
- The invader will always take this path if blocked by Cliff.
Rule 5. Each Terrain is against different specific invader(s) by killing or slowing them down.
Key strategies to protect your plant in PSG
The ultimate goal of the Plant Defense is to keep your plant alive for as many turns as possible. There are some tips to achieve this goal and to show a structure-driven approach in this game. Here are the former candidates’ five most popular strategies in the Plant Defense mini-game.
Build your defenders from inside-out and multi-layers
In the first wave, place your defenders in the inner layer, but some candidates advise that you should not build the defense only in the layers close to the plant. In addition, one experience shared that you should arrange the predators and terrain to maximize the coverage of the invaders’ path. “If the area covered by predators overlaps with plant, then you waste precious square of predator power.”
Various former participants of PSG have reported the inside-out methods to help them reach the highest turns with minimal resources to protect the plant. They usually last around 32-35 turns, which is a good score for this game.
Identify the pattern of the invading pest
This isn’t so much a “technique” as it is a notice to remember – after 15 rounds, you won’t be able to alter or add more resources. Try to notice the invaders’ pattern and immediately adjust your approach appropriately. It will take a few rounds to determine what works best for each invasion.
The candidates have observed pest patterns and concluded: “It’s best to secure straight lines like North/South and West/East from the plant.” They also shared tips on avoiding wasting resources: “I wasted too many resources making a full circle around.”
Use the powerful defender wisely.
Reports from the candidates show that you should place your most powerful resources closest to the plant and expand with the less powerful but longer-range ones. The candidates usually received the new defenders/terrains with the most damage at the third wave. Therefore, do not hesitate to place them in your barriers to maximize their effectiveness and hold the invaders for longer. “When you get a new defender at the end – use it; most likely, it will be the most powerful one.“, said this year’s McKinsey candidate.
Make careful calculations
The candidates shared their struggle with calculations of the move due to the time pressure. One candidate shared, “Now, I wish I had spent a bit more time on that to do the calculations correctly.” Some tips that could help you avoid time waste are
- Use your resources prudently, and create all-around protection for the plant – lopsided defenses (i.e., heavy in one direction, but weak in others) won’t last long – and lasting longer is the objective of this mini-game.
- One important thing to note in the game is that you must choose the correct terrains and defenders for the invaders you are trying to block or destroy since different terrains and defenders only affect SELECTED invasive species. Or else, you can be easily defeated shortly after the 15th turn.
Make necessary changes in your plan
Since you need to be highly calculative for your moves in the first phase, feel comfortable editing your plan as and when you take turns and make changes to your plan basis the population of the existing species and new species. There will be unpredictable patterns of the invaders, or you might miscalculate while placing in the first few moves. Be agile with your plan, and always remember that the goal is to protect the plant for the longest time possible.