Review
SimCity

Top 10 Most Influential AI Games

Alex J. Champandard on September 12, 2007

Welcome to the AiGameDev.com list of the most influential AI games of all time! You’ll find video and computer games that have used artificial intelligence in innovative ways to critical acclaim, and some of them that have managed to integrate cutting-edge AI technology too…

#10
Sim City

Sim City 1

Screenshot: A small coastal town in Sim City 1.

Released: 1989
Developer: Maxis

30 Second Pitch

SimCity is a simulation and a city-building game that spawned a best-selling series. You get a plot of land to build residences, industries and many other buildings to keep the inhabitants of your city satisfied.

Innovations in Game AI

  • As the first of the “Sim” series, SimCity pioneered a new form of gameplay: controlling a complex simulation.

  • Each element of the city is modeled in a realistic way, using AI if necessary (particularly in the most recent versions of the game).
  • The emergent properties of the system are perfectly balanced to keep the player entertained.

#9
Half-Life

Half-Life 1

Screenshot: A scientist chatting with a security guard.

Released: 1998
Developer: Valve

30 Second Pitch

Half-Life is a sci-fi first-person shooter featuring Dr. Gordon Freeman, a theoretical physicist stuck inside an underground research facility when teleporting experiments go wrong unexpectedly.

Innovations in Game AI

  • The cut scenes are entirely interactive. A combination of scripting and AI is used to avoid interrupting the gameplay (i.e. you can use the crowbar to destroy things while being told what to do next).

  • An AI security guard accompanies the player through some levels early in game.

  • Squad AI is used effectively for the first time in the latter stages of the game.

  • Despite not using any revolutionary technology, the AI is very well tweaked and integrated smoothly into the storyline.

#8
Total War

Shogun Total War

Screenshot: An army in Shogun: Total War marching over the hill.

Released: 2000-2006
Developer: The Creative Assembly

30 Second Pitch

Total War is a series of games combining turn-based strategy on a Risk-like map, with real-time tactical control of battles on a 3D terrain.

Innovations in Game AI

  • Thousands of AI-controlled soldiers are featured for the first time in a fun and interactive game, without noticeable performance problems.

  • The game models the emotions of groups of soldiers, essential for simulating battles accurately. This logic is inspired by the book, The Art Of War.

  • The Total War engine is used on TV by the History Channel as part of the Decisive Battles series.

Read Flanking Total War’s AI: 11 Tricks to Conquer for Your Game.

#7
Thief

Shogun Total War

Screenshot: Two guards in a room in Thief.

Released: 1998
Developer: Looking Glass Studios

30 Second Pitch

Thief: The Dark Project is a single player stealth-based game played from a first person perspective. The main character is Garret, a master thief applying his trade in a medieval/Victorian setting.

Innovations in Game AI

  • The game uses an accurate sensory model, allowing the AI actors to respond realistically to light and sounds. The whole game is based around this technique.

  • The AI actors use audio recordings to voice their current state, letting the player understand what’s going on.

Read Sneaking Behind Thief’s AI: 14 Tricks to Steal for Your Game.

#6
The Sims

The Sims

Screenshot: A family inside a house in The Sims.

Released: 2000
Developer: Maxis

30 Second Pitch

The Sims is a life-simulation of the daily activities of a family of virtual characters in a suburban house. The player gets to design and build the house, as well as guide these “Sims” through the day.

Innovations in Game AI

  • Smart objects are used to help implement the behaviors. The object specifies how each character interacts with it, which has many scalability and workflow advantages over centralized logic.

  • The Sims each have basic desires which drive their choice of actions.

  • The emotional interaction between the characters is also modeled, which allows for relationships.

Read Living with The Sims’ AI: 21 Tricks to Adopt for Your Game.

#5
Creatures

Creatures

Screenshot: The cartoon world in Creatures.

Released: 1996
Developer: Millennium Interactive

30 Second Pitch

Creatures is an artificial life program where the user ‘hatches’ small furry animals and teaches them how to behave. These “Norms” can talk, feed themselves, and protect themselves against vicious creatures.

Innovations in Game AI

  • It’s the first popular application of machine learning into an interactive simulation.

  • Neural networks are used by the creatures to learn what to do.

  • The game is regarded as a breakthrough in alife research, which aims to model the behavior of creatures interacting with their environment.

Read Evolving with Creatures’ AI: 15 Tricks to Mutate into Your Own Game.

#4
Halo

Halo

Screenshot: Halo’s Master Chief in combat.

Released: 2001
Developer: Bungie

30 Second Pitch

Halo: Combat Evolved is a first-person shooter where the player assumes the role of the Master Chief, battling various aliens on foot or in vehicles.

Innovations in Game AI

  • Enemies use cover very wisely, and employ suppressive fire and grenades.

  • The squad situation affects the individuals, so certain enemies flee when their leader dies.

  • A lot of attention is paid to the little details, with enemies notably throwing back grenades or team-members responding to you bothering them.

  • The underlying “behavior tree” technology has become very popular in the games industry (especially since Halo 2).

Read Teaming Up with Halo’s AI: 42 Tricks to Assist Your Game.

#3
Façade

The Sims

Screenshot: Grace and Trip talking to the player.

Released: 2005
Developer: Procedural Arts

30 Second Pitch

Façade is an interactive story where the couple is invited to the apartment of Grace and Trip, a couple who has a relationship breakdown. The player can coach them using full typed sentences.

Innovations in Game AI

  • The player interacts with the game by tying text into a natural language parser.

  • The underlying behavior language provides ways to specify the behavior of characters in terms of a dynamic story.

Read Chatting Up Façade’s AI: 23 Ideas to Talk Your Game Into.

#2
F.E.A.R.

The Sims

Screenshot: Enemy soldiers in F.E.A.R. getting shot down.

Released: 2005
Developer: Monolith Productions

30 Second Pitch

F.E.A.R. First Encounter Assault Recon is a first-person shooter where the player helps contain supernatural phenomenon and, naturally, armies of cloned soldiers.

Innovations in Game AI

  • The AI uses a planner to generate context-sensitive behaviors, the first time in a mainstream game. This technology used as a reference for many studios still today.

  • The enemies are capable of using the environment very cleverly, finding cover behind tables, tipping bookshelves, opening doors, crashing through windows…

  • Squad tactics are used to great effect. The enemies perform flanking maneuvers, use suppression fire, etc.

Read Assaulting F.E.A.R.’s AI: 29 Tricks to Arm Your Game.

#1
Black & White

Black & White

Screenshot: A creature casting a spell in Black & White.

Released: 2001
Developer: Lionhead Studios

30 Second Pitch

Black & White is a god game which includes elements of artificial life simulations and some strategy. The player rules over an island populated by various tribes, and can teach a large animal-like creature to do his/her bidding.

Innovations in Game AI

  • The gameplay is focused on the interaction with a large AI creature which can learn from examples, and takes reward and punishment.

  • The design integrates artificial life within the context of a strategy game.

  • The engine uses a solid AI architecture, rooted in cognitive science, known as belief-desire-intention (BDI).

  • Machine learning techniques such as decision trees and neural networks are used with great success.

More technical AI reviews of AAA games.

Discussion 12 Comments

Andrew on September 13th, 2007

Hmm, interesting list. I've started reading a game AI book, and it lists some other games I would have thought more important then Halo at least (which has nothing revolutionary at all on Half-Life, and don't even get me started on the dumb allies you get in Halo). They have (which are not on your list): Ultima Underworld: The Stygian Abyss - for brand new things - NPC's in a world with AI, and the world was 3d too. Dogz - A virtual dog! I even remember this game - good simulation, and fun too. Tamagochi - Representing one of the first commercial uses of A-life technology (released before Creatures) The Last Express - I'm currently playing this, a neat game, or rather interactive movie. Amazing use of a full cast of NPC's which are autonomous (and are programmed with AI and given tasks, rather then entirely scripted - leading to multiple endings and ways to do, or not do, tasks). I don't take credit for putting up these alternatives, and they didn't have a top 10, just a historical list, but I do agree you're missing a few influential ones - although I do agree that perhaps halo is influential to AI purely for selling a lot (as much as how it's level design is influential, or its weapons, or its online play...etc), same with FEAR. I also hope the order doesn't matter, I don't think apart from the FPS's any of the influences overlap :) So I do agree, those are all influential games in the AI department - not all as influential as each other, and most covering different areas. I'd be interested to see if Civilisation would come on a longer list if it is influential to its own genre due to its age and how well it sold, and other games might match the criteria in their respective field (that racing game which employed neural nets, and respectively high AI's in other genres). PS: I know, I know, its a opinionated, top 10 list, which cause my kind of comments. I think perhaps it would have been cooler to do 10+ posts on each game in a series of "Influential games" with a more in-depth look at each one, I'd certainly be interested in that more then a long comment on this single post :)

alexjc on September 13th, 2007

Thanks for your comment Andrew. I've not played the games you mentioned (except Civilization, a lot :-) but I will look into them. The Civilization series was on my mind, but I didn't feel any other game could be replaced... I put Halo and F.E.A.R. so high up on the list of influential games for very specific reason. Both Damian Isla and Jeff Orkin (respectively) have written very extensively about their work on the AI in both those games, and the technology has inspired the whole industry. Just from consulting, or talking to friends in other companies, many game studios are using one of these two techniques (i.e. behavior trees or a STRIPS planner, respectively). I call that influential! I don't think I'm too far off, but hey, this list is meant to be controversial :-) Alex P.S.: You anticipated my master plan for in-depth weekly reviews very well! I also felt it would be of value to write about each one in more detail. P.P.S.: Suggestions for other AI Games are very welcome... That was also part of the plan!

Andrew on September 14th, 2007

You have not played a Tamagochi?! Madness! :) I also see your reasons much more clearly now - if this is how influential the games are at this very second, it might be true Halo and FEAR come near the top, they are a lot newer then most of the others. And I will await any further more in-depth look at these games :) and if you miss any I think that brought something new to the table or were influential, comment so that you know of them. Civilisation (+Alpha Centuri) is one series (like Sim City) which brings several influential things, although I have not played the newer ones, such as personified world leaders (with their own personalities most importantly), strategic long turn-based play which means careful planning is needed (not done for the AI in the first few games though...), and so on.

Dil on September 18th, 2007

I'm surprised not to see Oblivion in this top 10. With their Radiant AI and their goal driven AI, they made a good step toward realism.

Andrew on September 18th, 2007

Oblivions Radiant AI, apart from handling up to 20 or so NPC's in an area, really is nothing on some other RPG's which do much better day/night behaviour, better guards, routines, etc. It didn't really have anything good for the designer either since the way you could alter it in their AI editor was poor :(

Joshua on September 21st, 2007

Hi Alex, System Shock 2 was influential on me at least. I'm not sure how much of a hand Ken Levine (shameless name-drop - he's the man) had in the AI side of the development of that fantastic precursor to Bioshock but irregardless i would suspect that it inspired many others to create behaviours that reinforce immersion in story focussed games. From recollection, didn't Thief use the same engine as system shock 2? The dark engine or some-such.

paulmeister on July 3rd, 2008

A few criticisms and what not... There are some important game titles that you left out, namely Outcast and Oblivion. Also your list of innovations, while good, is lacking and I believe should go further to expound upon what exactly made the AI so great. And more importantly, you might want to list what is lacking with the AI, since game developers often seem too intent on the eye candy to develop a truly innovative game experience. I really wasn't that impressed with Half Life's so-called squad AI. Namely because a game called Outcast came out years earlier, with about as good of an enemy AI model as I've ever seen to date. Guards patrolled cities or sat around their camp, passing time. If they spotted you, they would get up and pursue you. They might signal others over to help, or pull out a horn to let others know of your presence. If you hid... underwater, or behind some good cover, they would lose track of you and begin to search around. You could see them shield their eyes from the sun as they scanned the terrain for your presence. It was all very convincing. Enemies would try to dodge your fire, and sometimes would hit each other by accident. I would comment on Oblivion and others, but not enough time or space at the moment.

paulmeister on July 3rd, 2008

Ok, in Oblivion, if you or an NPC does something "bad" (i.e. attack another character) the guards seem to think that justifies death by swording and proceed to hunt down the offender until they fall. What ever happened to arrests? If you DID engage them in combat, they should do like real guards would, and yell to drop your weapon. If you drop it, they should stop assaulting you and simply grab you. They should also pick up any weapons and items lying around in the area and store those in the prison's loot box, as well. Games just aren't as sophisticated and thoughtful as I wish they were. These things seem so obvious...

paulmeister on November 21st, 2008

Far Cry 2 is another example of a horribly overrated game that could have been so much more than it was. The much touted ability of the game to present you with different ways to complete missions and then adjust dynamically based on what you choose is laughable, since almost every time, regardless of whether you choose option A) or option B), the result is always C). You can never deviate from the storyline if you wish to progress in the game. A perfect example: In a dramatic turn of the story, you must pick whether to 'help' your friends at the bar, or those stuck in the church. Regardless of your decision, the result is the same! - the enemy knocks you out before you know what happened, and you find yourself stranded in a sandstorm as part 2 of the story begins. Enemy A.I. gets the job done and not much else. Plenty of behavior inconsistencies, such as becoming suddenly aware of your presence when you are hiding nearby, being able to shoot right at you and track you through heavy foliage when you can't even see their muzzle flashes, daring to drive right up to you and then getting out directly in front of your mounted machine gun (no sense of self-preservation). There are countless other examples but these are some of the worst. Also, buddies will not get into vehicles with you or even stay with you on foot. The only things that get high marks from me are the expected: Graphics - excellent, Sound - superb, and Voice Acting, when it is during a scripted sequence, is done extremely well, though unscripted enemy chatter leaves plenty to be desired (more variety and context-sensitive dialogue would be nice). Also, vehicle driving mechanics are crap. And don't give me the excuse that it's expected in a FPS'er, because all it means is they were to lazy and/or cheap to implement a better handling model, such as that used in Colin McRae driving games. But what else can be said? The gun-play feels realistic and is a blast, despite not being able to wield a P90, and despite that around 90% of the weapons are useless in most situations. But it's what happens when developers care more about release dates and marketing a product than spending the time and money to make something truly worthwhile and innovative. As a result, I've been playing the same 3 games for 5+ years now and will not buy another game until it proves itself to be worthy of it's time.

paulmeister on March 27th, 2009

Just finished the much touted F.E.A.R. and it has given me a new respect for Far Cry 2. How ironic is that. I hate to be oppressively negative, but it's just how I see it... F.E.A.R. feels like I'm playing a 10 year old Rainbow 6 game without the strategy and with pitiful A.I. The poly count and detail of the world in general was also noticeably poor. With all graphics set to maximum, a computer mouse in the game looked like a rectangle with trimmed corners. Ick! Enemies don't pursue you beyond their "comfort zone". If you retreat and close a door, they never come open it to find you. The game is a sloppy rip off of Max Pain meets Half-Life, with a few parallels possibly borrowed from certain Anime series like Bubblegum Crisis 2040. My main issue however, is with how abysmally mediocre the gameplay is, in contrast to the hype that surrounded it at release. Enemy behavior is heavily scripted and pre-planned and basic and boring. They will move from one hiding spot to another and will peek around corners or sick their gun over to shoot blindly at you, but that's about it. They do chatter to each other and appear to communicate and use strategy, but if you pay attention, the things they say are mostly random and is essentially just a smokescreen to hide the fact that it is really just basic A.I., nothing fancy or innovative. The graphics and world are so bad though... at least Far Cry 2 looks good and is halfway fun to explore. You can't use stealth tactics at ALL in F.E.A.R, because apparently every soldier has natural night vision. At least you CAN sneak around soldiers at night in Far Cry 2. I'm sorry to anyone who bought F.E.A.R. and likes it, but it is not going to be on my list of recommendations anytime soon.

premium on April 5th, 2009

[B]Grimheretic,[/B] You're absolutely right and thanks for taking the time to read the article & title rather than scan the list! There's definitely enough for another article of most controversial and under-rated AI games :-) Alex

premium on April 8th, 2009

Left 4 Dead would definitely be high up on the list, but this was written before it came out. It may not have been technically revolutionary, but in design it was and its influence is visible on the industry as a whole. Again, Halo's technology had a huge influence on developers -- particularly thanks to Bungie's behind the scenes talks. People like Griesemer, Butcher, Isla did way more for the industry than anything we learned about Half-Life 2. If nothing else, Damian Isla helped popularize behavior trees, which is a huge step forward. Alex

If you'd like to add a comment or question on this page, simply log-in to the site. You can create an account from the sign-up page if necessary... It takes less than a minute!