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Zomb... AI Movement Mechanic

15 replies [Last post]
Joined: 09/20/2010


Been continuing to work on "Zomb...", a semi co-op game about survival. ( )

Trying to make it as simple as possible while still retaining a sense of realism.
One problem that I've really hit a wall with is; how should the Zombies move?

In the current version the zombies spawn outside the house, and each zombie movement phase they move towards the closest human character.
This really doesn't feel so smooth though, as the players have to check the closest character for every zombie, and which direction decreases the movement the most.
Plus there might be two equally viable ways to move, who makes the choice then ?

The zombie movement mechanic should be trying to surround and close up on the characters.
Since they spawn in all different directions, the 'Move towards the closest' mechanic kind of works to surround them since they will be closing in from all different angles.

The house is built up with rooms, some huge rooms may be split up in parts (Think Mansions of Madness)

Do you guys have any better ideas how to control the movement of the zombies?
I don't want to have to include a player that plays on the zombie side from the start.


Joined: 04/18/2009
Can you not use the same

Can you not use the same system they use in Castle Ravenloft?

You can find the rules on if you ar intrested in how the monsters move there. Basicly they move from tile to tile. While the heroes move from square to square. (a tile consists of several squares)

Joined: 09/20/2010
There aren't really any

There aren't really any squares in the game, instead every room more or less functions as tiles in the sense of Castle Ravenloft (played Wrath of Ashardalon recently).

This system is really how it works now, the zombies move 1 tile closer to the closest character.

But I find it a bit too slow to move all the zombies, when the players need to check the closest character, and the fastest route to that character PER zombie.

Would like to find something that works faster, and require less "calculating" per zombie.
In a way, they've worked around that in CR/WoA by only having some monsters activating at a time, when only player A's monsters activate after player A's turn. I guess something like that is possible...

Thanks for the idea :)

Joined: 05/15/2010
Movement categories

Is it possible to assign movement categories to various zombies? Arkham Horror has a similar movement for monsters based on category. For your game maybe the zombies spawn from some random pull where players are unsure of what type of zombie they have until it is placed. Then just detail some movement categories so that they still move to surround but in various fashions.


Joined: 04/08/2011
You can use 2 dice to do

You can use 2 dice to do random movement.
The one dice would have sides marked 0 forward, 0 back, 2 forward, 2 back, 3 forward, 3 back.
The second dice is marked 0 left, 0 right ect.
This way you get random basic AI movement.
You can add terrain effect bonusses, penalties and re-rolls if you need it to be more complex.
Obviously your zombies stop moving randomly once they hear/see someone.

Hope this helps.

Joined: 05/15/2011
Possibly fast to play rules

This is my very first posting here, so please bare with me if I'm talking nonsense.

I'd make the zombies rather dumb, so your calculations get easier. I case it makes them too weak, you can compensate by making them faster/more numerous/more powerful. I'd separate the zombie movement into two parts:
1. Move to the closest character in case a character is really close.
2. Move using a different rule otherwise.

Ad 1. Consider a character to be close only in case it's no more than (let's say) 3 tiles away and/or they lie on a straight (horizontal/vertical) line with the zombie. Here you'd need to find out what exact "distance" is easy enough to spot the closest character at the first sight. When determining the closest character (and/or the move direction) gets too time-consuming, it's not worth doing (you want to spend your time playing, not counting fields...).

In case there are multiple closest characters, you either need to choose one of them or to compute movement for both of them and resolve it somehow:
- You could use a die here, but rolling a die takes time, and so does interpreting the result.
- You could let one player break the tie at their will (the player owning a "zombie-mover token" would do it and pass the token to the next player).
- You could make the zombie move "more in its preferred direction" (how ever you interpret it). The preferred direction could be simply defined as towards the house center, or it could be more complicated. You could print an arrow on each tile determining the preferred direction. That's surely very fast and error-proof.

I see, I've got a whole bunch of ideas now, but no idea if anything of it fits.

Ad 2. In case there's no character close enough, check the zombie position relative to all characters as a whole at once:
- In case all characters are above and left to the zombie, move diagonally up and left
(assuming diagonal moves are allowed and there's no obstacle). The same for the symmetric cases.
- Otherwise, in case all characters are above the zombie, move up. Symmetries again.
- If the above does not apply, move simply in the preferred direction.

Gimbal's picture
Joined: 12/03/2009
dramatic “risk assessment”

Perhaps you can rationalize the situation depending on drama?
Instead of the practical “move to the closest” that many such games use, you could try something like “risk assessment”.

Rooms/tiles away from the players stack up chits with secret “zombie value” (Something in the scenario tells you how many chits is generated and where). They do not move. Therefore less calculations.

Only when players enter a tile/room they turn over the chits and are attacked. Also, maybe loud noise/explosions/smell of blood makes stacks move closer to the player, or redistribute somehow. But that needs some rules similar to the ones listed above.

Good luck!

Joined: 07/28/2008
Radius Movement

You could even have it as ranges.

Generally zombies don't move they simply mill about in the tile they are set up at the start of the game. Once a player reaches line of site the zombies in that area will move 1 tile closer to the player in view (much like Tannhausers Pathfinder system I guess).

If noises are made then zombies in the surrounding tiles will move closer.

melee = zombies with 2 tiles will move in the direction of the noise
gunfire = within 3 tiles of the noise
explosion/grenade = with 5 tiles of the noise.

Joined: 12/01/2010
What if Zombies mill about

What if Zombies mill about until a player moves within X distance of them.
That get's them "noticed" and the Zombie will chase that player - and not switch targets, unless they get attacked, in which case they switch targets.
You can make it so that if the Zombie is a certain distance it reverts back to its idiot mode.

In a possibly more simple explanation:

Zombies have 2 modes:
1. Mill about mode - they move not at all or randomly
ends: player moves within X distance - move to Chase mode targeting triggering player
2. Chase mode - zombie moves in the most direct path to its target
ends: player moves greater than Y distance - move to Mill mode with no target
ends: zombie attacked by player other than target - move to Chase mode targeting attacker

pelle's picture
Joined: 08/11/2008

Is the map static or randomly generated? Looking at the description of the game, with the focus on coop/competition and the blood cards etc, I guess the map layout is secondary? Because if it can be the same every time there are many simple ways to script semi-random movement paths for the zombies, until they get close enough to start hunting someone. Could let you focus on the important parts of the design, and make zombies that require less boring time to figure out which way they are headed.

Joined: 09/20/2010
Thanks for all the feedback

Thanks for all the feedback guys. Definatelly a lot of good suggestions :)

And about if the map is static or randomly generated. Honestly, I haven't given it much thought yet, however generally I prefer random setups, but a static map could be just fine and its easier to balance as well.

Joined: 09/20/2010
An idea that Ive had in the

An idea that Ive had in the back of my mind is ;

Whenever a player does an action or movement, they place "presence"/"noise"/"activity" (haven't decided on the name ;) )tokens, and these tokens alter the behaviour of the zombies, by redirecting them and determening where they move.

Say if player A moves, he first place one token in his current room, then move the character to the next room. In the new room that player decides to do an action, say search for items, and then having to place a new token in that room.

This way there'd be lots of tokens in rooms where several players are in, and less where only a single character is. Different actions could also increase the amount of tokens that are placed in the rooms.

This could also be used with the traitor mechanic, as a player about to turn into a zombie can start to lure the zombies to different locations.

One way one could use this would be that if theres a room with say, 3 tokens. Zombies within 3 spaces of that would be heading towards that room. And if theres a room within 1 space containing 1 token that zombie would move to the closest room (or the room with most tokens?).

But here again it ends up to ; Who choose where they go if theres several rooms equally far away with equal amount of tokens... And the worst part of this is, the players would have to check this for each room containing zombies, which isn't the fastest :(

Oh and if there are no rooms with tokens in them, they'd in one way or another move aimlessly around in the house.

le_renard's picture
Joined: 10/08/2010
I must confess I have no idea

I must confess I have no idea right now about how you could resolve those issues, but I really like this "noise" tokens.. I'm quite sure there's something to do with it.
Very thematic !

Joined: 09/20/2010
Just thought I'd share the

Just thought I'd share the latest updates:

I really didn't come up with any good ideas for two weeks. Then yesterday (while showering) it hit me, I've been narrow minded and only been visioning rooms and zombies moving towards the players (like mentioned in this thread). Why do I need the rooms? What does it add to the game? Not really much, except some theme maybe.

So I started to think about, in what other ways can it be solved, and then I came up with the idea that instead of having rooms connected to eachother where the players and zombies roam around in, just have 1 location card that represents the human parties current location.

This location card can have some special abilities and some other stats. And the human party can move to other locations, by drawing a new location card and discarding the old. This is slightly more abstract, but the whole thing gets a lot faster so I'm ready to take the chance.

I've decided to keep the "noise" mechanic, and now it works so, that the players generate "noise" by doing different actions, and after all the players turns, theres an "encounter" phase. In the encounter phase, zombies spawn and the more "noise" you've made, the more zombies may spawn. (ie, for each noise, there a chance a zombie spawns)

Any zombies that aren't killed remains in play, making more and more piling in on them.

I've yet to playtest this, but I'm working out the most basic features in my head (and sketchbook), and I should be able to do a simple playtest soon, since this really made everything more streamlined and easier to implement. Hopefully it'll work well enough to keep.

Just thought some of you might be interested :)
Any feedback is welcome, as always!

le_renard's picture
Joined: 10/08/2010
Hi again... may I suggest you

Hi again...
may I suggest you take a look at this nice ( and french ) light and fast paced card game calle Off The Dead ?

Joined: 09/20/2010
Thanks for the link, watched

Thanks for the link, watched the tutorial and it seemed pretty interesting.

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