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Heroes!

We hope you are all well in this new year!

We are cracking on with work on Vermintide 2, which includes the upcoming Chaos Wastes and, of course, continuing filling those hourglasses on the character select screen with new careers for the heroes! But this dev blog is not about either of those things. We want to take a few paragraphs to talk about bots - specifically upcoming improvements to bot behaviors coming to PC in patch 4.2.

Gameplay Programmer Ričardas will talk a bit about the improvements that he and the team have been working on in relation to some of the feedback you have given.

NEW RANGED COMBAT BEHAVIOR AND TWEAKS:

One of the tools bots did not utilize very well that players do is ranged combat. Whilst ranged combat is not the focus of the Vermintide 2, it is still a very useful tool that helps to ensure the party survives against the bad guys - specials in particular.

Sure they know how to pull the trigger but ranged weapons, unlike their melee counterparts, are a lot more specialized and have a limited ammo supply. Wasting shots on poorly chosen targets is extra painful. So in Patch 4.2, we have added some ‘target categorizations’, which should make bots better at dealing with specials if they are equipped with snipe type weapons (eg. handguns, crossbows), select more fitting attack type if they have such available (eg. fireball staff, bolt staff). So for example they shouldn’t fire handguns at infantry, and won’t try to kill special units with weapons like the Drakegun.

BOT POSITIONING:

Good positioning is a hard thing to achieve since you need to take in a lot of information and make some predictions, too. For players we have a bunch of visual cues that help them identify danger like toxic clouds or streams of bullets, however, bots don’t see the way we do. So the way we try to keep our bots out of trouble is split into two parts.

Navigation Mesh Cost Weights are used to help bots navigate around fixed static dangers, such as globe gas or lamp oil fires.

Emergency Threat Areas are employed by bots to move them out of more dynamic threats. They tell bots that something bad is about to happen in an area and should get out as fast as they can, such as a Chaos Warriors hulking great axe bearing down towards their face.

We have made some changes here, as well as added and updated a bunch of those areas to help our fellow bots avoid and react more quickly to imminent threats. Also, we have tweaked the emergency threat response behavior to be less “panicky” which resulted in them sometimes slipping off cliffs.

BOT MELEE COMBAT TWEAKS:

Staying together is key to survival in Vermintide, making sure that bots stay close when a horde (or a patrol that someone just pulled) is approaching makes them more reliable at covering your flanks and saving you from a special. With that in mind, the higher the apparent threat on the battlefield, the more likely bots are to stand at your side, whilst favoring faster, sweepier attacks against infantry class enemies.

As a bonus, it also reduces the amount of times bots charging forward into hordes and incidentally running into your crosshair, but that will still happen especially when there are less enemies around.

BOTS BEING TOO COMPETITIVE ON RESOURCES:

Bots are supposed to fill more of a support role and make sure the player gets to be the star of the show, so when a bot claims a resource, whether that’s ammo or a potion, it indirectly steals fun away from the player.

For a while now, bots have been quite hungry for resources. We’ve made some tweaks to that in 4.2, such as restricting them from picking up ammo bags if the player is missing any ammunition, and made some adjustments to their dependence and willingness to picking up and chugging potions.

Patch 4.2 will be coming in the next few weeks, and with it are also some general bug fixes for bot behaviours, and with it we’ll compile patch notes that break down in a bit more detail the commentary above.

Yeah bots have a tendency to eat attacks not directly targeted at them. It has been a big problem. You can even easily tell what is going to hit or not hit them it’s that predictable.

Well it’s also a matter of bots replacing players temporarily in a lot of situations too, right? It’s not always a player or two just want to play by themselves (although sometimes those matches can be nice). Bots interject when a player disconnects or leaves and they can be there as a filler in the start of a match until more players join. So it’d be nice if the bot didn’t kill itself so quickly by doing things like:

• Chasing specials to its death
• Running into Ratling Gun fire to try and kill it
• Running through fire and gas to chase a special
• Eating overheads directed at other characters
• Chasing bosses and fighting in horrible locations rather than relocating to the player
• Endlessly trying to grab an item you ordered it to grab but it teleport/chains to the players and can’t get the item. So unless something like the player ordering the bot to grab something else, filling the bots item slot for that item you ordered it to grab, etc., it will forever try to run to get that item because we can’t cancel that command for them and they won’t “teleport grab” the item like they sometimes do with grims or tomes.

The list goes on.

Taking potions is fine because they always give them to players. Just remember that any item they can give a player, you don’t need to force them to “not pick up”. Ammo bags make sense, but make sure they always pick up ammo from infinite sources (ammo crates). Also take into account if the player has infinite ammo weapons like drakeguns/Sienna, a player running away from ammo, a player has all but one of their shots, tons of ammo bags around from Ranger Vet or something like Boom Boom suicide rats, etc. If a bot is missing 50% of their ammo and a player missing 1 of their handgun shots, bot should probably just pick it up anyways. In general, I have greatly favored bots being hungry for resources rather than purposely starving themselves.

All in all, sounds like a bunch of great changes for bots. A necessity indeed and it can only benefit this game and act to help Darktide too as time goes on.

This fix requires more than just us twiddling some code about. These APIs we’re using are fairly new implementations from Valve, and we’re having to relay information to them for them to investigate. It’s an effort spanning multiple teams over two continents. We do wish it were as simple as fixing a bit of our codebase but it’s more far reaching I’m sorry to say. It’s impossible to say right now where the issue lies, but do know we’re not treating this as a mild inconvenience.