The State of Game AI 88
Gamasutra has a summary written by Dan Kline of Crystal Dynamics for this year's Artificial Intelligence and Interactive Digital Entertainment (AIIDE) Conference held at Stanford University. They discussed why AI capabilities have not scaled with CPU speed, balancing MMO economies and game mechanics, procedural dialogue, and many other topics. Kline also wrote in more detail about the conference at his blog.
"... Rabin put forth his own challenge for the future: Despite all this, why is AI still allowed to suck? Because, in his view, sharp AI is just not required for many games, and game designers frequently don't get what AI can do. That was his challenge for this AIIDE — to show others the potential, and necessity, of game AI, to find the problems that designers are trying to tackle, and solve them."
Re:An example of great game A.I. (Score:3, Insightful)
RTS/TBS: build stuff quicker then you can and/or advance technology faster then should be possible.
FPS: Have 'super accurate' shots, higher health, bigger guns.
This to me is a huge downfall of modern games - instead of making AI opponents "smarter", devs simply tweak the rules to give the AI more of an advantage.
That being said, it is incredibly hard to define an AI that doesn't have "unrealistic" skills when the players' skills are advancing in the same fashion. For example, your skill in Halo is to a large extent determined by how accurate you are, which is easily mimicked by AI. I can't count the number of times I've heard someone accused of using an "aimbot" because their skill (or luck) in an FPS seemed "too good" or "unrealistic". The same goes for RTS games - the top human players in the world are to a large degree measured by how many commands, or actions, they can perform in a minute - which is again easily transferred to an AI opponent.
In my humble opinion, what we need is some sort of standardized test for game AI - put one player and one computer opponent in the game with the exact same capabilities, and see who comes out on top after repeated rounds. After all, it's impossible to claim the AI is "cheating" if it can't do anything that you can't. And whoever learns from the other's actions best over the course of the game will come out on top. And if at the end of the day the two are evenly matched, I will happily put down money for the game.
Re:An example of great game A.I. (Score:3, Insightful)
The problem there is that the two factors you mentioned (accuracy and commands-per-minute) are both things that AI can far exceed humans at, especially if you aren't careful to limit it. I think that the real solution is to make a game where learning and adapting is more important than accuracy or speed, but then someone would have to write actual AI.
Yeah, wouldn't it be nice to have games like that again? I blame the original "Nintendo generation" games for the proliferation of the abominations that are RTS games. In my experience, the contrived demands of the "Real Time" aspecs so completely dominate the game that what little "Strategy" remains might as well not exist.
Re:An example of great game A.I. (Score:5, Insightful)
When working on the RTS Empires: Dawn of the Modern World, we had a difficulty setting that was truly insane. The enemy wasn't a computer pretending to be a human, it was an impenetrable black wall of impending dismemberment. If you really wanted to defeat it, you had to pile-on 7 vs 1, with at least 3 top-notch players overseeing the operation. Those were long, intense, brutal battles... Helping to bringing down that beast was a real badge of achievement. Unfortunately we had to cut it back a bit before release for technical reasons, but the ability is still there.
A realistic FPS would have the enemy sneak up behind you and stab you before knew they were there. A realistic racing game would end in firey death the moment you accidentally rode up on the curb. A realistic tactical squad shooter would have your men pinned down by heavy opposition fire until they called in an airstrike on you. A realistic war game would involve lots, and lots, of digging.
This is a long way of saying that AI isn't about promoting hyperrealism, but rather is in service of making the game fun.
That having been said, I'd kill for 3D pathing that doesn't suck. If I need to do another escort mission with some idiot who can't walk around a boulder in the middle of the road, I'm going back to Tetris and I'm never leaving.
Game buyer doesn't care (Score:3, Insightful)
As someone who wanted to develop better AI for games, I'll say this : the state of AI didn't change because there is no customer need for it.
When AI becomes a selling feature, then it will be given more consideration by developpers AND allowed more resources by managers.
Which may be never, as it faces a tough adversary : the 'ooooh Shiny' whizz effect of graphics.
Most humans aren't that smart (Score:5, Insightful)
The Problem that AI is supposed to solve in most Games is not "how to beat the human".
The Problem is "how to make it fun for the human".
Creating an AI that can consistently beat humans is not hard. Making it fun for most humans might not be so easy.
Fact is humans aren't that good at most games (amongst other things). You don't have to be very intelligent to be good at most games. How many of you can beat a computer at chess at high difficulty? How many people actually _lose_ in tic-tac-toe - I've seen more than a few
It's often not hard to make a computer extremely good at a game, at least good enough to beat most people. But does that make it fun?
In most FPS games, stupid humans want to be able to mow down _thousands_ of stupider computer controlled enemies - "against the odds". That's what makes it fun for them.
That's just not possible if the enemies start having a lot more brains. Then most players might have difficulty getting past the first 3 enemies
It's not that difficult to make an enemy FPS "bot" have superb tactics, coordination, timing etc. Especially if the map is pre-known (which is usually the case). You can code the tactics and heuristics in. If you hear the player in position X, group A enemies head to position Y and group B head to position Z, and bye bye player.
Imagine if enemies that are low in health kept running away and hiding, and then snipe at you from far away when they see that you are busy doing something else. While that might be more realistic, it might not be so fun eh? Who really wants realism in games?
At that rate the player can never pretend to be the hero he wants to be. He'll just be dead. And your game won't sell.
Same goes for RTS games, believe me, you don't have to make a computer cheat to beat humans - a computer can micromanage better than most humans.
Just ensure that basic stuff like navigation is better. Stuff doesn't have to be that smart, but at least they shouldn't be totally stupid - they should be able to walk around stuff without getting stuck - even a "dumb" animal can navigate open spaces better than many computer controlled stuff in games.
Re:Game buyer doesn't care (Score:1, Insightful)
It's mostly the fault of mainstream game producers There are not many [widely distributed] games where the player needs to use their brain to succeed....consider any games for which gold farm sweat shops are plausible.
Most games are not designed around awarding intelligence ( to the general chagrin of the /. community) but it is the reality...people who can think critically are the extreme minority, and game companies generally cater to the majority (lowest common denominator)
I could ramble on, but my target audience will surely be able to fill in the blanks for themselves
Re:An example of great game A.I. (Score:5, Insightful)
It's trivial to program a computer to beat humans in most games.
But the problem AI is supposed to help solve in games is not "How to beat the human".
The problem AI is supposed to help solve is "How to make it _fun_ for the human, so that lots of humans will pay $$$ to play".
Most people would have near zero odds against a top notch computer opponent - FPS, RTS, whatever.
Does anyone really think that Starcraft, Doom etc would have sold so much if playing them was like playing against a World Champion or two?
I've seen the top humans play in FPS and they can aim pretty well. You'd never be the Hero winning against the odds if the _thousands_ of enemies you fought were even only half as good as a world champion.
Developers need predictable behaviour (Score:3, Insightful)
As a game developer myself, I can tell you one of the reasons why game developers often use finite state machines for AI instead of advanced neural networks that employ clever learning machine learning algorithms: It's orders of magnitude easier to analyze and understand (and thus debug and fix) how and why a FSM does what it does than a complicated neural network.
When you're making a game, you want results that are easy to predict and easy to schedule - if you decide to make advanced AI and train the NPC behaviors, it's hard to schedule and very hard to pinpoint and definitively fix a problem where one or more NPCs suddenly start acting extremely strange and un-human. And it's hard to fix if they become to clever.
It's one of those cases where simple models can get you most of the way, and it's more reliable and it's much cheaper to develop (in terms of processing time and implementation time).
Re:Most humans aren't that smart (Score:4, Insightful)
However, bots like that aren't any fun. It's more fun if the bots have limitations that at least somehow resemble the limitations players have; can't turn quickly, nor move too fast, know the map by instinct, etc.. Then, within those constraints, use AI and use AI well.
Put a limit on how many commands the enemy can do in a certain time for FPSes - or a limit on the rapidity it can issue commands in RTSes.. and suddenly you have a much more interesting problem. Or for that matter, let the player decide how smart the enemy should be, and whether or not it can cheat (issue a thousand orders in a second?). If he likes playing against a cheating bastard, let him play against a cheating bastard; if he wants to play against a chessmaster with no mobility and all brains, let him do so, that he'll be surprised when it still beats him.
Yes and no (Score:5, Insightful)
1. I'll somewhat disaggree about RTS. Sure, in theory it sounds good, but I've yet to see a strategy game where the AI doesn't plain old cheat to stay alive.
Yes, it can "micromanage" better, in the sense of cycling through all units every frame or couple of frames. Sure, it can do a "for" loop better than a human. But actually allocate resources intelligently, apply smart tactics against a human who built in the unexpected place, etc, is where computers are still as stupid as it gets.
Again, we could argue about theoretically being easier to make them smarter, but way I see it, that's the basic rule of thumb: does it need to cheat? Does advancing in the storyline to face a new enemy, described as more cunning and ruthless, actually just mean the same retarded AI with a bigger pre-built base and more silos full of spice/tiberium/whatever and more reinforcements out of nowhere? Does it just mean that the new "cunning and ruthless" enemy just gets better units from the start? Does upping the difficulty actually just means that the AI gets even more money and a damage bonus, as opposed to just un-hobbling that supposedly super-AI a little?
If any of those are true, no, you have _not_ coded teh uber-AI and then dumbed it down for the player. You can claim to have a too smart AI when it can start just with a town centre and 2 peons, just like the player, and put up a better fight. And, oh, make it run just as long a way to the mines/geisers/spice-fields as the players, at that. Starting with 3 resource nodes in an already built base doesn't quite qualify as equal difficulty.
2. Yes, chess makes a good poster child, but that has had decades of real AI research into just that speciffic game, and at that by real AI researchers. A brand new game, with brand new rules, within 3 years, and with the cheapest team possible... heh... sorry. I can't take that seriously.
Most of the games so far have even trouble pathfinding, or keeping their flamethrower guys from frying their own team mates in front of them, etc. Or look at bigger scale strategy games, like Paradox's, where it takes several years of patching just to get the AI to no longer waste its whole army attacking Switzerland. And even then often the "fix" isn't as much AI, as just making fortifications randomly disappear in combat, so eventually the mountains around Switzerland just stop giving a defense bonus. You know, 'cause apparently 100,000 soldiers with rifles and grenades can demolish a mountain. And then invariably it becomes vulnerable in some other way, to some new exploit created by the previous fix.
3. Ditto for FPS. What the computer has as an advantage isn't really better AI, it's unerring accuracy. It's trivial to make a bot that never misses, and has faster reactions than any human, because it simply needs to calculate the angle and pretend it aimed accurately that way. It simply doesn't have the whole issue of moving the whole arm with the mouse, or the finite resolution of the mouse, or the whole lag of the pipeline from mouse to seeing the cursor move (the TFT alone introduces another 1-2 frames lag) which is already known to ruin one's accuracy because it lets you overshoot before seeing any results, etc.
Some cheat even further, by basically having eyes in the back of their head, or being able to see through walls, or just not having the issue of "does that 3 pixel tall figure over there look like one of our guys or one of theirs? Is it even a human?" It just doesn't have to parse an array of pixels, it already knows where everyone is. Even when you say "if you hear the player at position X", you're already cheating. A player can at most judge "I hear some footsteps in that general direction" (and even that at best in 30 degree increments), but not an exact position, nor know if it's a friend or foe or neutral there.
Give the computer a spread comparable to a human for the selected difficulty level, give it a similar lag in reacting and turning, and limit it to the exact same field of view, and that suppos
Re:An example of great game A.I. (Score:4, Insightful)
If I need to do another escort mission with some idiot who can't walk around a boulder in the middle of the road
That is why I hate, hate hate, HATE escort missions and missions where you must keep some AI character alive in games. It's one thing to deal with a stupid AI enemy (perhaps a little laughable, but not frustrating). It's quite another to deal with a stupid AI ally. Basically, in most of the games I play on higher difficulty settings, the ally AI's are just cannon fodder. Anything else is just damned annoying (especially when you can't even command them to get down or take cover).
There are a few games that do this right: Halo 3 (which makes vital character invulnerable and everyone else dispensable), Half-Life 2 (which periodically replenishes your cannon fodder AI allies and makes the one non-cannon fodder character near-invulnerable), and Mass Effect (where you can command your allies directly). And there are also games that do it wrong, like Oblivion (where your allies on escort missions don't scale as well as enemies, can't repair their weapons and armour, and do stupid shit like walk off cliffs).
Re:Most humans aren't that smart (Score:3, Insightful)
In most FPS games, stupid humans want to be able to mow down _thousands_ of stupider computer controlled enemies - "against the odds". That's what makes it fun for them.
That's just not possible if the enemies start having a lot more brains. Then most players might have difficulty getting past the first 3 enemies :).
It's not that difficult to make an enemy FPS "bot" have superb tactics, coordination, timing etc. Especially if the map is pre-known (which is usually the case). You can code the tactics and heuristics in. If you hear the player in position X, group A enemies head to position Y and group B head to position Z, and bye bye player.
Imagine if enemies that are low in health kept running away and hiding, and then snipe at you from far away when they see that you are busy doing something else. While that might be more realistic, it might not be so fun eh? Who really wants realism in games?
At that rate the player can never pretend to be the hero he wants to be. He'll just be dead. And your game won't sell.
I see your point, but disagree to a certain extent. Idiot AI in modern FPS really devalues the successes, at least for me, to a large extent. It should be an incredible accomplishment for a single man to kill a squad of 5 people, but it's just one encounter, and I feel nothing afterwards. If the AI could be juiced up in these games, then you wouldn't need to throw a 1000 enemies at the player to make them feel like a hero, because you'd feel more accomplishment from each encounter.
I recently just played through Deus Ex for the first time, and it is an outstanding game, especially for the time. However, the AI was really the Achilles Heel in terms of immersion in that game. At times, you can really get into games like that, but once the rules of the AI start to become apparent the whole experience starts to feel less like you're a hero, and more like a toy world. You shoot a guy in the chest, hide for a while, he decides it must have been the wind and goes back to his patrol without telling anyone. The whole thing becomes so exploitable that it just feels cheap.
Furthermore, in many FPS like Deus Ex or Halo, your character is so super-powered even with intelligent foes, he would still be a walking death-dealer. If he's not enough of one, you can always just make his shield that much stronger.
Lastly, when you add in intelligent AI for tactics, you'd also want to add it in for realism. Enemies that run low on health usually (though sometimes they might if their courage rating was high) wouldn't run away and snipe you. That's not realistic AI. They'd run away and cry that they'd been shot, and yell for help from their teammates who'd go and try and assist them.
Re:Most humans aren't that smart (Score:2, Insightful)
"Just ensure that basic stuff like navigation is better. Stuff doesn't have to be that smart, but at least they shouldn't be totally stupid - they should be able to walk around stuff without getting stuck - even a "dumb" animal can navigate open spaces better than many computer controlled stuff in games."
A lot of games -- even high profile games like Halo 3 -- can't get this fundamental down. God forbid you have an AI character driving your Warthog anywhere. You're sure to ram into a tree or rock & get hopelessly stuck. Some older games have done it right. The original UT had a nice user-variable scale of skill for its bots & you could opt for bots which ramped up their skill to match your performance. And the original Half-life grunts seemed like NPC geniuses to me: retreating when under pressure, throwing grenades to cover their retreat, & then flanking... That game is 10 yrs old, but few games seem to have achieved that level of AI optimization.