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Zombie Smarts

I have been playing some more 7 Days to Die (7DTD) now that the Alpha 17.1 patch came around. There have been a lot of tweaks to the progression mechanics and Perk system, including some level-gating on Iron/Steel tool recipes. The biggest change, however, was to zombie AI.

In short, zombies are now impossibly smart… and impossibly dumb.

It’s been long enough that I don’t even remember how zombies behaved in prior patches. What zombies do now though, is behave in perfect tower defense intelligence: the shortest distance between them and you, with walls adding a virtual number of steps. Zombie are also perfectly prescient, knowing exactly which wall blocks have the lowest remaining health, and will attack that spot en mass to get to you. At the same time, zombies prefer not attacking walls to X extent, if they can walk there instead.

The result? Cue the Benny Hill theme:

Essentially, the current 7DTD meta is to not create bases at all, but rather mazes that funnel zombies into kill zones and/or large drops that loop them around until they die of fall damage. The devs have added a “zombie tantrum” mechanic to try and get some damage on looped mazes – zombies will attack anything nearby when they fall, possibly weakening your support pillars – but that will be metagamed away with multiple platforms or deeper holes.

To be clear, the prior zombie meta was solved by simply building an underground bunker. At that time, zombies could not dig into the ground, and disregarded the Z axis entirely – it was possible to hang out in the middle of a bridge and often have a nice grouped pile of zombies directly below you to hit with a Molotov. I played the game enough to recognize which Point of Interest had a pre-built bunker located underneath it, and often sought it out immediately after spawning so I could all but ignore the titular 7th day horde attack.

That said, how smart should zombies be?

The only way to answer that question is to ask what the game you’re making is supposed to be about. When you add tower defense mechanics, you get a tower defense game. This will preclude people from building nice little houses in the woods, and instead opt for mazes and obstacles and drops. It becomes a much more technical game, solvable with very specific configurations. Having dumber zombies frees up a lot more base designs, on top of possibly requiring a lot more attention to one’s base after an attack, as a single “dumb” zombie could be weakening a support in an unused corner.

My initial “solution” would be to mix and match, but I think that’s actually the worst of all possible worlds. Instead, I think zombies work best as environmental hazards. Bunkers might make you invulnerable to nightly attacks… but you have to leave sometime. Shouldn’t the punishment for hiding underground be the simple lack of information of what’s going on, combined with having to spend your morning hours slaying the zombie hordes milling about outside?

I guess we’ll see what the devs eventually decide. At present, there simply seems to be a maze-based arms race at the expense of any sort of satisfying nesting. If the 7DTD devs want to double-down, well… thank god for mods.

Dynamic vs Random

Keen has another post up lamenting the stagnant nature of modern MMO game design, while suggesting devs should instead be using ideas from games that came out 15+ years ago and nobody plays today. Uh… huh. This time the topic is mob AI and how things would be so much better if mobs behaved randomly dynamically!

Another idea for improving mob AI was more along the lines of unpredictable elements influencing monster behavior. “A long list of random hidden stats would affect how mobs interact. Using the orc example again, one lone orc that spots three players may attack if his strength and bravery stats are high while intelligence is low. A different orc may gather friends.” I love the idea of having visible cues for these traits such as bigger orcs probably having more bravery, and scrawny orcs having more magical abilities or intelligence — intelligence would likely mean getting friends before charging in alone.

The big problem with dynamic behavior in games is that it’s often indistinguishable from random behavior from the player’s perspective. One of the examples from Keen’s post is about having orcs with “hidden stats” like Bravery vs Intelligence that govern whether they fight against multiple players or call for backup. Why bother? Unless players have a Scan spell or something, there is no difference between carefully-structured AI behavior and rolling a d20 to determine whether an orc runs away. Nevermind how the triggers being visible (via Scan or visual cues) undermine all sense of dynamism. Big orc? Probably not running away. If the orc does run away, that’s just bad RNG.

There is no way past this paradox. If you know how they are going to react based on programming logic, the behavior is not unpredictable. If the behavior is unpredictable, even if it’s governed by hidden logic, it is indistinguishable from pure randomness. Besides, the two absolute worst mob behaviors in any game are A) when mobs run away at low health to chain into other mobs, and B) when there is no sense to their actions. Both of which are exactly what is being advocated for here.

I consider the topic of AI in games generally to be one of those subtle designer/player traps. It is trivially easy to create an opponent that a human player could never win against. Creating an opponent that taxes a player to their limit (and not beyond) is much more difficult, and the extent to which a player can be taxed varies by the player. From a defeated player’s perspective, there is no difference between an enemy they aren’t skilled enough to beat and an unbeatable enemy.

You have to ask yourself what you, as a hypothetical designer, are actually trying to accomplish. That answer should be “to have my intended audience have fun.” Unpredictable and tough mobs can be fun for someone somewhere, sure, but as Wildstar is demonstrating, perhaps that doesn’t actually include all that many people. Having to memorize 10+ minute raid dances is bad enough without tacking convoluted mob behavior outside of raids on top. Sometimes you just want to kill shit via a fun combat system.

Themepark MMO players enjoy simple, repetitive tasks – news at 11.