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Posts Tagged ‘Civilization’
One of the more intruiging lectures of the 2008 GDC was given by Soren Johnson (MobyGames info) ex- of Firaxis and now with Maxis on the “Spore” team. He was talking about how Civ 4 fit in the spectrum of game AI between two extremes… “Good AI” and “Fun AI”. Here’s some selections from my notes on the lecture. (Forgive the seeming lack of lucidity – I was typing like a madman!)
Also, this is a direct link to Soren’s Slides (.zip) on his blog – which is where the images in this post came from (click to enlarge).
â€śGoodâ€ť AI (Play to win)
â€śFunâ€ť AI (Play to lose)
For example, Aggro in an MMO is fun AI.
With tanks, healers, DPS (damage per second) there is a formula for handling it… Trivial AI problem to â€śsolveâ€ť by the players.
What are the best environments?
Tactics available to AI?
The question is: â€śPlay to win or Play to lose?â€ť
With Civ IV, the AI does have limited options. There are a lot of options that they do not put on the table for the AI. Esp. with diplomacy. E.g. fighting a war… as a player, you can ask them for stuff if you promsie to quit war, then attack them over again. AI doesnâ€™t do that.
Every player is differentâ€¦ some want things like challenge, sandbox, narrative.
For narrative, you want to aim for personality, for the AIs to maintain memory about you. It’s OK for them to fall for traps. They built that into the leaders in Civ 4.
With regard to the challenge, you “want player to win or at least understand WHY they lost.“
Need for difficulty levels:
Where does cheating fit?
The Noble level in Civ 4 is the â€śeven levelâ€ť with regard to production modifiers, etc.
But Noble has other cheatsâ€¦ e.g.
The AI needs more help in these areas.
For example, AI does not leave cities empty like a human wouldâ€¦ so unit support costs. Human army and AI army will never be the same size because they have to keep units in their citiesâ€¦ therefore cut the support costs for the AI since they need to have a larger army.
Cheats should NOT be linearâ€¦ certain you want to help more or less as you progress your diff. levels.
Civ 1, 2
Civ 3, 4
Information cheats can really backfire on you. E.g. Amphibious Assault Judo using empty port cities in Civ 3. (solved by determining random time for updating the assault target, ignore temporary data such as nearby units.)
Only two of these can be trueâ€¦ Soâ€¦ should AI sell techs cheaply? Solution? Can AI pursue altruism?
When the AIs were trading often, it made for very even technology levels between all players rather than some groups ahead and others lagging. Everyone had everything.
Solution in Civ IV
AI can undersell by 33% butâ€¦
Arbitrary rules e.g. â€śI will never trade Iron Working with you.â€ť
What is the point of cheating?
Designing for the AI?
Traditional testing fails
Probabilistic Reasoning – Weights to factors, values to situation
Data-driven Mods – AI was stand-alone so that it was compiled into dll. CvGameCoreDLL.dll was 100% independent of engine.
Soren Johnson, AI guru behind Civ 3 and Civ 4, posted an interesting tidbit on his “Designer Notes” blog entitled “A Farewell to Civ“. He mentioned that since he is no longer with Firaxis (having moved over to the Spore team), his GDC lecture next week will really be his last hurrah in speaking about his work with the Civ series.
One thing’s for sure, I will be avoiding writing about Civ 4 in Post-Play’em until after I attend this lecture. One quote caught my eye:
Essentially, I will be talking about the difference between thinking of the AI as the playerâ€™s opponent and thinking of it as simply an extension of the core game design (what one might call the difference between â€śgoodâ€ť AI and â€śfunâ€ť AI). There will also be a long section on AI cheating – the bane of my existence for many years – concerning which type of cheats are acceptable to players and which type are not, using Civ as an extensive case study. Further, I hope to prove that, for Civ at least, there is no such thing as – and never could be – a â€śfairâ€ť difficulty level where the AI is playing the same game as the human. Your mileage , of course, might vary.
I don’t want to make the mistake of assuming something he did was cheating, or something I thought was cheating was actually brilliant AI work on his part!
Cheating or not, he has done some exceptional work in making Civ 3 and Civ 4 an absolute delight to play… even as an AI guy. I’m looking forward to meeting him.
Look for updates from GDC both here and in the IA News blog.
Sid Meier, strategy game designer and gaming icon, will be receiving a Lifetime Acheivement Award at this years Game Developers Choice Awards at the Game Developers Conference in San Francisco this February.
I am currently beating my head against the wall that is Civ 4 at the moment, and got many years of pleasure out of the original Civilization and especially Civ 2. I also remember vividly playing F-15 Strike Eagle in the mid-80s and later F-19 Stealth Fighter. Because of what he has meant in my gaming history, I will be honored to be able to be present for this ceremony. Sid Meier truly is one of the great game designers in the industry and I personally salute him and thank him for his contributions.
Congratulations, Sid! Keep it coming!
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