heroes Under the Hood AI Improvements

[Stan 5,244]

AI is an important element of Heroes of the Storm and Blizzard has been working hard on improvements. The updated AI can now stutter-step and has faster reaction times.

• Blizzard is transitioning the AI from being controlled by scripts to being controlled by new systems built into the game engine.
• AI should feel more responsive, accurate, and execute more dynamic strategies.
• The AI can now stutter-step to keep attacking while moving into position.
• All Heroes released since Garrosh use the new system, and with each update, more Heroes are transitioned to the new system.

Blizzard (Source)

AI is an important part of Heroes of the Storm. A significant number of games are played versus AI, and PvP games also have AI-controlled Heroes when players are disconnected. Those ever-helpful, ever-pesky minions and mercenaries are AI, too! We are passionate about bringing the best possible experience to all our players, so the AI team has been working hard on improving our AI systems. Read on for details!

What makes good AI?

There are many ways to define “good” AI, but from our perspective it’s an AI that closely matches players’ expectations. Minions and bosses need to be predictable. AI Heroes need to be very skillful. Players expect their AI Hero allies to stay safe, but also engage in team fights at the right time. There is a delicate balance between staying safe and capitalizing on opportunities. We also try to ensure the AI supports human players a little more than AI allies.

Valla Vaults into position for a Rain of Vengeance, but Stitches rescues the human player from annihilation!

Making good AI has its challenges. Many situations are complicated enough to have several valid strategies, and expectations can vary from player to player. We work closely with the game designers on our team to develop AI that models all the factors they consider important in decision making. And although we are trying to make the AI as smart as possible, we only give them access to information a regular player would have so they don’t get to cheat!

What is changing?

We are gradually transitioning the AI from being controlled by scripts to being controlled by several new systems built into the game engine. We are not trying to make the AI drastically different, but we are building systems that can be extended easily to add a lot more detail to the AI. You may notice AI Heroes being more responsive, more accurate, and executing more dynamic strategies.

Speed!

The new AI system runs many times faster than before. This has not only resulted in a slight improvement to the frame rate of the game, but it has also allowed us to update the AI more frequently! AI now have faster reaction times and they can use abilities in rapid succession. We had to drastically limit the update rate for lower difficulty AI!

Tactics

The tactics the new AI use has been enhanced to allow for a rich set of targeting options, and better positioning during fights. Examples are being able to predict the movement of targets, find clusters of targets, and filter or prioritize targets in many ways. Our designers have had a lot of fun using these new options to create more detailed AI. Kel’Thuzad’s surgical use of his abilities is a great example of this.

 

Rather than simply moving into range of their targets, AI Heroes also try to stay out of danger. They calculate a score for many locations around the target and move to the safest one.

The AI are also now able to stutter-step to keep attacking their target while moving into position.

 

Strategy

The AI has a new system for making strategic decisions. There are many things on a map that Heroes could be doing, and each of those is considered a potential goal for the AI. Each goal has a score calculated for it and the AI Heroes on a team are then assigned to the most suitable goal. This algorithm tries to maximize the team’s chances of winning by gaining experience in lane, taking mercenary camps, and controlling map objectives. It also looks out for lone enemies that can be easily ganked—so watch out!

Development

The team is constantly working on new Heroes, Battlegrounds, and game modes. To support this rapid development pace, we created an AI editor, which allows our game designers to quickly customize each Hero’s AI. This results in higher-quality AI that has been tuned for each Hero’s play style. You may notice this when Azmodan sees you at low health and throws a long-range Globe of Annihilation to finish you off!

A major part of the new AI is a “behavior tree” system, which is a common AI technology used in games. It is called a “tree” because it branches at every possible decision the AI can make, and the ends of the branches are the actual things that the AI can do, such as moving or attacking.

The branches of the tree are modular and can be customized for different AI behavior depending on the unit, map and game mode. This type of system is essential for supporting a diverse range of Heroes and Battlegrounds.

A very small number of the 400 nodes in Valla’s behavior tree.

Future

All Heroes released since Garrosh use the new system, and with each update of the game, more of the older Heroes are transitioned to the new system. We have plans for more improvements to AI systems too, including better danger avoidance, strategic decision making, and tactical behaviors. Please reach out on the forums with any feedback you have. We are determined to make our players’ experience with AI as enjoyable as possible.

Now, grab a friend and test your mettle versus the AI in the Nexus! Good luck.

[Valhalen 1,484]

One thing I have been noticing is that indeed some AI Heroes are more responsive and active than others; some even respond to pings immediately.

Also, I wonder, when a player disconnects, they're is replaced by an AI of what level? Veteran? Elite? Or a completely different AI from the VS AI format?

Something else I ever wondered. Is it me or in VS AI higher difficulty Heroes deal more damage? I noticed a strikingly difference between the damage dealt by Veteran and Elite.

[Lovestud500 2]

Looks like the medic still likes to tank. Pretty sure in ranked the AI gets replaced by easy bots.

[mtmf 14]

I wonder if that means they finally taught Valeera to use her stealthed skills...

[ArusVicious 156]

This is certainly one of the best changes I've seen to this game in ages. Love how they keep improving everything and aren't forgetting about those who like to play VS AI or just happen to come across somebody who disconnects in QM. To imagine the work that goes into having them be so smart and calculate all of these things (possibilities and options are limitless) is extremely impressive. This right here is why I love Blizz.

[CyberDVonaven 82]

If this is the case then it would be nice if Blizzard would list all the heroes that have had their AI versions changed over to the new system. And then ones that have been added/changed over in any new patches that come out as they do so. So we all have a better idea of this when fighting in AI matches or end up with AI controlled allies (or enemies) in any other matches.

Edited September 14, 2017 by CyberDVonaven

[Valks 2,377]

14 hours ago, Valhalen said:

Something else I ever wondered. Is it me or in VS AI higher difficulty Heroes deal more damage? I noticed a strikingly difference between the damage dealt by Veteran and Elite.

I think they make different talent choices, or properly use their talents. Kael'thas is a good example, with the use of their D on different spells.

[Valhalen 1,484]

1 hour ago, Blainie said:

I think they make different talent choices, or properly use their talents. Kael'thas is a good example, with the use of their D on different spells.

I'm not sure, I think they deal slightly increased damage overall, regardless of talents.

[MurkyFelix 51]

2 hours ago, Valhalen said:

I'm not sure, I think they deal slightly increased damage overall, regardless of talents.

I've kinda noticed that that seems to be the case too...like I feel like I get blown up way more quickly in Elite even when I'm playing safely/well. I'm not really complaining as it does get you better/less likely to run in but it would be nice to get the exact feel for damage done to you from enemies in general (so you know how much you can push it for want of a better way of saying it)

[Razah 1]

This is really nice! While playing versus AI yesterday, they even captured the boss, that was AMAZING.

[Valks 2,377]

4 hours ago, Valhalen said:

I'm not sure, I think they deal slightly increased damage overall, regardless of talents.

I've been trying to test this, but with Auto-select AI, it's a real P.I.T.A because you can't guarantee the heroes to compare.

[Kurosu 58]

Instead of reacting to a problem they should strike at its root and punish the people that leave mid game or even at spawn after blaming matchmaking.

[Valhalen 1,484]

3 hours ago, Blainie said:

I've been trying to test this, but with Auto-select AI, it's a real P.I.T.A because you can't guarantee the heroes to compare.

Blizzard should add an option in VS AI where you can select your allies/enemies (when playing with an AI team). This would be also a good to practice against specific matchups.

[WhitherWhy 0]

Not sure if Zarya was the best choice to illustrate stutter-stepping...Nonetheless, I look forward to these changes!

[Spec 2]

I'd rather have pathing improved before AI but whatever

[SteveFrost 97]

Maybe something like OpenAI that trashed Dendi, Arteezy and the others will be upon HotS soon(tm).

Also, guys, wanna listen a funny story? Was queueing for a brawl one day, it was taking a while, and you know, you get that message "AI allies & enemies may be added to shorten queue times." I get to a game eventually and... it was me vs another guy; the other 8 players were all AIs ECKS DEE.

I won in the end c:

[Valks 2,377]

On 9/14/2017 at 7:57 PM, Valhalen said:

Blizzard should add an option in VS AI where you can select your allies/enemies (when playing with an AI team). This would be also a good to practice against specific matchups.

Yep, not sure why they wouldn't implement it to be honest. They have AI for every hero, so why not?

[Caldyrvan 377]

While you ask them, ask for invisible mode in the APP, please :D oh and the option to turn off "save replay" and not being forced to save them.

[Valks 2,377]

7 hours ago, Caldyrvan said:

While you ask them, ask for invisible mode in the APP, please :D oh and the option to turn off "save replay" and not being forced to save them.

The community has been asking about invisible mode since the app released :p

[Caldyrvan 377]

I know, that's why I mentioned it :)

[Valks 2,377]

20 minutes ago, Caldyrvan said:

I know, that's why I mentioned it :)

We'll probably still be talking about it in 2020, thinking back to when we asked for it.