Zombies will start turn 1 by infecting one territory from each player, and adding +60% troops on those territories, without attacking anyone.
On turn 2 the Zombies will start by adding +75% troops to each territory (often this calculates to 'double minus 1 troop') before they do their attacks following the pathing route
Zombies will always try to get to 55% of all troops on the board, and if they feel they are too far behind they might grow a lot in one turn.
In extreme cases they might add as much as +150% on all territories just to catch up.
Exactly how much the zombies will add each turn is collerated to how many troops the other players have, and how many zombie troops have been taken out. But you can usually follow this table as an reference.
If all 5 human players have 20 troops each, they have a total of 100 troops. For the zombies to reach >40% of all troops on the board they would need to have at least 67 troops. Growth is pr. territory they hold
| Turn | <40% | <50% | <55% | >55% |
|---|---|---|---|---|
| 1 | Infect +60% | |||
| 2 | +75% | +3 troops | +2 troops | +1 troop |
| 3 | +90% | +3 troops | +2 troops | +1 troop |
| 4 | +105% | +3 troops | +2 troops | +1 troop |
| 5 | +120% | +3 troops | +2 troops | +1 troop |
| 6 | +135% | +3 troops | +2 troops | +1 troop |
| 7+ | +150% | +3 troops | +2 troops | +1 troop |
Infections are a mechanism where the zombies just take over a random territory that you own, with all the troops on it.
Zombies might infect players if they have <40% of all troops. Zombies will never infect the same player twice before all players have already been infected once.
The fewer territories the zombies hold, the higher are the chances of infections
They are more likely to infect larger stacks when they first infect a player
Every territory on the map have its unique number (index), and the Zombies will always start attacking from the lowest number possible.
For every attack, they will always try to attack the neighboring territory as specified by the game devs (primary path). If that is already taken by Zombies or hold a player stack too large to attack, it will go on to attack the next priority territory (secondary path) etc.
With some clever work by the RISK community we have been able to extract this information and create pathing maps showing both index numbers and the zombies prefered pathing.
You can find these maps under the RISK Maps section of this website.
If you have defeated all other players and are only facing a huge Zombie army, here are some tips to clean them up:
