Goals – AI Wars part II

It’s the end of the year and AiGameDev.com is having an open nomination session for best game AI’s of 2007. One of the categories is for Indie Games. What I really like about the competition is the following from the AiGameDev website:
Remember, you’re giving an award for the best artificial intelligence in a game. This means it must be a balance of two things:

Entertainment — The AI in a game isn’t supposed to behave perfectly; in fact it’s often supposed to make mistakes in a convincing way. So, are the non-player characters (NPC) or non-character AIs fun to play with or against?

Intelligence & Believability — Do the in-game actors fit in with the design and story? It’s not purely about smarts — but it helps!

Of course, the two are not mutually exclusive, on the contrary! The best games each year successfully use intelligent behaviors to create a fun experience for the players.

I’d like to tell you that I intentionally programmed into the AI for Armageddon Empires all the boneheaded moves that you might occasionally witness. As I’ve explained before the role of hidden information plays a large part. And to be honest the limits of the AI play a large role as well. When it comes right down to it the AI is just a collection of competing goals. There are over a 180 goals covering everything from building resource collectors to evacuating heroes when somebody like Nod is on the loose. Which goals are selected and what priority they are given determines how the AI will play. Here is a screen shot from my development environment that shows some of them:

AI goals

So the big three elements to the AI are:

1. Which Goals are selected

2. What priorities they are given

3. What they actually do when they are “processed”

Goals can also contain subgoals which is an aspect where it gets really fun and interesting. I created goals of 3 different basic types: Top (the big idea goal), Atomic (no sub goals) and Composite (a goal that sits in the middle and holds sub goals).

I’m a workman type AI builder. I enjoy reading the theory but I am not its master. I have an electrical engineering degree from almost 2 decades ago that helps me get a foot in the door but what I built for Armageddon Empires was very single minded and goal oriented (pun intended). If I had to accomlish something I scoped out what I needed and then scowered the web and fell back on my programming books. Speaking of which here are some of the books that I found really useful:

Programming Game AI by Example by Mat Buckland

AI Game Development by Alex J. Champandard

AI for Game Developers by Bourg & Seemann

AI Game Programming Wisdom (All of them) edited by Steve Rabin

Goals For the Future:

Improve the AI’s evaluation of and response to the opponents’ grand strategies.

Improve and expand the use of influence maps to identify key geography, danger areas and force dispositions.

Improve the system used for ranking basic things: Right now it is a mix of fuzzy logic and weighted sums…I’d like to try and expand the use of memory with the ranking system for things beyond animosity….and keep track of how goals performed.

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