Soren Johnson: The Chick Parabola

alexman

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I think this is quite relevant to Civ5 and 1upt...

Soren Johnson said:
On March 11, 2009 during the Three Moves Ahead strategy gaming podcast, freelance journalist Tom Chick introduce a phenomenon which has come to be known as the Chick Parabola:

My experience with Empire: Total War is this parabola of fondness. At first I don’t like it, so I’m at the bottom of the curve. I don’t like it because they do a terrible job with their documentation – it’s got a terrible manual; they want you to play through this scripted campaign if you want to learn anything; the tool-tips are really screwy. So, I’m hating it.

But then I’m playing it, and I’m learning it, and I’m liking it, so I’m climbing up that parabola. At the very top of the curve, I think, “Hey, I sort of figured it out. I like this game.” But then I start to discover that the AI is terrible, that it’s a dumb game, and I start coming down the far end of the parabola, and I am no longer fond of Empire: Total War.

Commonly, there’s this curve where I enjoy a game, and then I master the system, and then – unless it’s got a good AI – I lose all interest because I realize that mastering the system is where the challenge ends. Once I reach that point, the game is dead for me, and I hate that! That’s when the game should really start to take off.
Many veteran gamers will recognize this feeling from their own experiences – the rising enjoyment that comes from learning an interesting game system followed by an inevitable deflation as the challenge slowly disappears.

Sometimes, a simple technique or exploit becomes obvious that renders the rest of the game balance irrelevant. However, usually the culprit is a weak adversary as the artificial intelligence cannot grasp certain core game mechanics to offer the player a robust challenge. The problem is that the game’s designers have made promises on which the AI programmers cannot deliver; the former have envisioned game systems that are simply beyond the capabilities of modern game AI.

Symmetry Matters

Still, not all games suffer from the Chick Parabola. Many are so fundamentally asymetrical – Super Mario Bros., Grand Theft Auto, World of Warcraft, Half-Life – that the AI is simply a speed bump that can be easily tuned to provide the right level of challenge. The games which suffer the most are ones where the computer is forced to play the same game as the human.

These symmetrical games – StarCraft, Street Fighter, Puzzle Quest, Halo – have a unique challenge in that each game mechanic must not simply be judged on its own merits but also by asking whether the AI can reasonably understand the option and execute it successfully. Unfortunately, asking this question often disqualifies many interesting ideas.

Artificial intelligence is notoriously poor at handling issues of trust and betrayal, of long-term investments, of multi-front wars, and of avoiding traps obvious to any human. The question of trust, in particular, has torpedoed multiple attempts to make a viable single-player version of the classic board game Diplomacy, which relies so acutely on being able to read one’s enemies, one’s friends, and one’s supposed friends.
Thus, to avoid the Chick Parabola, designers of symmetrical games must weigh carefully the implications of various game mechanics. An interesting play option which over-taxes the AI runs the risk of making the game more interesting in the short-term – as the player learns the system – but less interesting in the long-term – once the player masters the system and can use the mechanic to run rings around the artificial intelligence.

Of course, designers of symmetrical games built primarily for multi-player – such as the Battlefield series or the fighting genre – can choose to sacrifice single-player longevity for multi-player depth. Non-conventional weapons are fine if we assume that veterans of the game are only interested in playing the game with each other.
The human brain is remarkably flexible, with the ability to easily process novel mechanics which are orthogonal to the rest of the game. This approach has many advantages; Valve has been able to radically change the multi-player-only Team Fortress 2 with each character update (giving the Demoman a sword and shield, for example) without having to worry about toppling over an increasingly rickety AI.
Designing for the AI

However, symmetrical single-player games need to be designed as much for the artificial intelligence as for the humans themselves. Even if painful, designers must be willing to leave some of their most orthogonal – and often most creative – ideas off the table for the sake of the AI. Game design is a series of trade-offs, and empowering the AI is important for avoiding the downward slope of the Parabola.
Nonetheless, creative developers can solve this problem at the design stage before it even reaches some doomed AI programmer. One game mechanic that pushed Chick over the edge with Empire: Total War was amphibious invasion. The AI was simply incapable of coordinating its land and naval forces together to launch a coherent and effective invasion of an overseas target. Smart players would quickly learn that if the AI could not attack amphibiously, then the strategic balance can be gamed easily. Maybe England’s troops are not such a threat after all?

This problem is not unusual; strategy games with transportation units almost always suffer from ineffective artificial intelligence. Coordinating land and naval units to be ready in the same place and at the same time – along with the necessary escort ships – is a non-trivial task.

Rise of Nations, Big Huge Games’s historical RTS, presented a blunt but effective solution to this problem; land forces which approach the shore simply turn into boats to carry themselves across the water. Once they reach their destination, the boats transform back into the original land units. No transportation ships ever needed to be built or managed at all.

With one simple stroke, Brian Reynolds, the game’s designer, removed a classic AI problem from the game, enabling water maps to remain interesting for veteran players. The design may have sacrificed the “realism” of requiring the player to build transport ships along with other naval units, but the upside was extending the game’s longevity significantly.

Furthermore, many design changes meant to bolster the AI by simplification often have the side effect of making the game itself more enjoyable for the player. Quite a few players did not miss having to build and herd transports in Rise of Nations. Civilization 3 and Civilization 4 introduced global unit support and city production overflows, respectively; both changes helped the AI manage its resources but also made the game more enjoyable for the average player by drastically reducing micromanagement.

Tough Choices

The designer’s biggest challenge comes when a mechanic which is demonstrably fun or core to the game’s theme needs to be simplified or dropped. Occasionally, a game can get away with assuming that a certain option will be human-only; in the original Civilization, Sid Meier added nukes to the end-game but didn’t allow the AI to use them. He reasoned that because the super-weapon came only at the end of a game with such scope, players who used them were not abusing the game; they were simply having a bit of crazy fun at the end.

Further, if the designer wants to maintain a mechanic that the AI can’t use, cheating is not a viable solution for balancing away the AI’s disadvantage. Allowing too many human-only systems effectively turns a symmetrical game into an asymmetrical one, which will eventually affect the strategic balance.

In the Empire: Total War example, once players know that the AI will never launch an effective amphibious invasion, the rest of the game changes immediately. Maybe players don’t need to bother defending their coastal territories? Maybe land-based allies are more important than water-based ones? Maybe the AI can be tricked into wasting its resources on futile invasions? Most importantly, the player is no longer playing like a queen – she is playing like a gamer who knows that the AI doesn’t work, one who is on the downhill side of the Parabola.

Ultimately, the designer may have to make a tough choice – drop a beloved mechanic or risk shortening the replayability? Many options do exist to extend a game’s longevity outside of pure balance – scripting a variety of scenarios, supporting procedural content generation, providing robust mod support, developing post-release content, and so on.

However, for robust replayability, nothing compares to pure strategic depth with a competent computer opponent. Sacrificing the game’s longevity to provide a few moments of fun for the human is essentially eroding the design at the foundation. As Chick puts it, when the player finally learns a system, “That’s when the game should really starts to take off.” The joy of learning is a big reason why games are fun, but no one wants to study for a test which doesn’t exist.

http://www.designer-notes.com/?p=287
 
Alex, long time no see ;) Welcome back :D

There was already some discussion about that exact parabola some time ago around here. We have to give credit to the man, since he was almost the only official reviewer that didn't painted the sky pink on civ V.
 
Even more than the parabola, I found Soren's point interesting, about designers sometimes having to cut features that the AI would not be able to handle. I remember being stunned when I learned Civ5 was going to add 1upt.
 
Even more than the parabola, I found Soren's point interesting, about designers sometimes having to cut features that the AI would not be able to handle. I remember being stunned when I learned Civ5 was going to add 1upt.
Fair enough :D I agree with you in that ... you, better than me ;) , know that even Civ IV AI had strong issues with handling the SoD it made, that is light years away of the brain power needed for handling 1 upt in a variable map enviroment. I was with hopes that they had inserted some cookie cutter formations and not letting the AI to war before it had one of those marching in good order, but it looks ( based in game experience ... no C++ code released so far ) that they didn't gone that way . The behaviour of ranged units is especially problematic and it looks that the AI does not scout before moving the units, that is a crass mistake.

Not that is was something unexpectable to see the AI trip in a so complicated feature, but to be honest, I was expecting a little more than what we see now in that regard :(
 
I thought this was going to be about relationships with women. Everything gets better until she discovers that you play Civ, then....
 
Hi alexman, nice to see you again. :)

Even more than the parabola, I found Soren's point interesting, about designers sometimes having to cut features that the AI would not be able to handle. I remember being stunned when I learned Civ5 was going to add 1upt.
I'd argue that there has been a change in design philosophy in the last 20 years with regard to the AI's capability of using the game's features. In the 90s, games emerged which were very complex, but which had AIs that actually failed in playing them decently. Two well-known examples are Master of Magic and SMAC. Still, both games had (and continue to have) many fans. From this, I derive 3 hypotheses:

1. A game with a weak AI can still be enjoyable for the player if it gives him enough interesting mechanics to explore. In terms of the Chick Parabola, this means that the parabola is designed so high that the player needs a very long time to get the feeling of having mastered the game.

2. AI programming has matured to a point where players now expect the AI to play the game decently. In recent years, developers of strategy games were reluctant to include features that the AI couldn't grasp at all (whereas in the 90s this wouldn't have been seen as much of a problem as long as the AI had a sufficient understanding of the game's core mechanics).

3. As a result, players are now less forgiving to incompetent AIs, and game developers are less prone to add player-only features. This makes a contemporary strategy game#s AI actually much more important than it was in the 90s. Because if the developers go in with a small amount of features (limited by what they think the AI can handle), and the AI fails to understand them decently, there's now no set of player-only features which might give the player fun despite the AI's failings, as long as he's still climbing the parabola.

Hmm, Soren would probably appreciate this development, as this makes his area of expertise even more relevant. ;)
 
It's nice to see you Alexman.

As a civ 4 developer do you think that it could be possible in future to have an AI as competent as in Beyond the Sword using 1upt?

Do you also think that the introduction of drastical changes to combat to improve the situation at this point are feasible?
 
Even more than the parabola, I found Soren's point interesting, about designers sometimes having to cut features that the AI would not be able to handle. I remember being stunned when I learned Civ5 was going to add 1upt.

do you mean that you were stunned to see them include this because you knew it would be difficult for the AI programmers to handle?

edit:
I thought this was going to be about relationships with women. Everything gets better until she discovers that you play Civ, then....

this is so true. i'd tell you some stories but they're way OT :D
 
Umm there is nothing here strategy gamers weren't talking about in the late 90s, possibly earlier...
 
Hi Alex. Nice to see you around Civ again. :)
 
Good article. Perhaps this explains the heavy streamlining of Civ 5 - all the interesting mechanics (e.g. espionage, diplomacy) were taken away because the AI didn't know how to use them?
 
So if the land units that turn into boats are good for the AI, how come the AI is unable to do any intercontinental invasions in Civ V? I've never even seen them try.
 
So if the land units that turn into boats are good for the AI, how come the AI is unable to do any intercontinental invasions in Civ V? I've never even seen them try.
In fact BtS had the exact same issue when you modded units to be amphibious :D In there is was because the units forgot their calculated path as soon as they changed domain not inside of a suitable transport. I just wonder if the thing is not similar here...
 
As a civ 4 developer do you think that it could be possible in future to have an AI as competent as in Beyond the Sword using 1upt?
Yes, definitely, but I think it would take a lot of work, and I'm afraid it would have to be done here by a bunch of civFanatics who know the game well. And unless the current code is seriously inefficient, a better AI would also require waiting for more powerful computers to arrive, since a more sophisticated combat AI would need a lot more computations between turns.

Do you also think that the introduction of drastical changes to combat to improve the situation at this point are feasible?
That's certainly not going to happen before the next expansion, if there is one, and only if they decide that the current system was a mistake.

m4gill4 said:
do you mean that you were stunned to see them include this because you knew it would be difficult for the AI programmers to handle?
Yes, it doesn't seem like they realized how much work it would be to implement this properly.

Rohili said:
Perhaps this explains the heavy streamlining of Civ 5 - all the interesting mechanics (e.g. espionage, diplomacy) were taken away because the AI didn't know how to use them?
I don't think so. I believe this was a design decision unrelated to the AI. Implementing the AI for diplomacy and espionage is way easier than implementing the AI for unit movement.
 
1UPT shouldnt be too complicated for the AI. We modern multi core CPU's, moving units effectively that doesnt take 1 minute to process should easily be possible. It really wouldnt have been hard to consult a couple of mathematicians to create an efficient algorithm to handle AI movements. Movements could have been totally predictable for the AI, hell, make it so his units always have +1 sight on higher difficulties if thats what it takes.

It doesnt take a veteran gamer to see that there is something seriously wrong with an AI that moves artillery units all by themselves. Not to mention the fact that when they have a gun perfectly placed inside of a city to potentially deal a lot of damage, they move it out of the city where one of my infantry units can easily take it out. Now I can shell the living hell out of the city w\o retribution, thanks!

For a game thats primarily single player, the AI seems to have been thrown together at the last minute. Ive been playing Civ V for like a month now (and I have never played a previous Civ) and I can consistently beat the AI on Immortal. I have taken half a dozen cities whilst killing dozens of units while losing one or two units. The AI being able to produce units on a 2:1 scale is no problem when you can kill them on a 6:1 scale on the battlefield.
 
Psyringe,

You mentioned Master of Magic as an example of a game with a poor-to-terrible AI which is still a lot of fun. I agree that it is still a lot of fun, but not because there are more mechanics to learn and master. (At least it is not entirely that.)

MoM provides challenges with the various monster lairs and node guarding creatures -- essentially barbarians which are not part of the AI empires -- that often are more difficult, and thus more interesting/fun, than anything the AI will generally throw at you.

I have played any number of games of MoM where developing my empire to the point I could take on the toughest lair and node dwellers -- sky drakes, various wyrms, etc. -- was much more important and interesting than the AIs. I eventually would run into the various AIs, and then crush them utterly a couple dozen turns later, before returning to fighting the "barbs". The skill of the AIs was pathetic, but they were not really the focus of the game so who cared?

Fall From Heaven does this as well with vastly tougher and more varied "barb" challenges, including special opponents like Orthus and the various specials associated with the Apocalypse Counter. These are actually dangerous enough that you have to make strategic decisions based on the possibility of them showing up, or gamble that they will not be close to you.

Civ IV and V barbarians are pretty bland, by comparison. Even with raging barbs turned on you generally only need to make small modifications to your usual choices, stepping up your total military effort but otherwise not really shifting your overall path.

Ideally the player would face strong challenges from both the AI rivals and the non-aligned forces such as barbs.
 
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