Re: Computer version of Risk
On Wed, 2 Jul 1997, Anders Eurenius wrote:
> > All AI programming is centered around 2 concepts:
> > 1) What does the computer player know
> > 2) What does he do about what he knows
>
> Ooh.. That's a very simplistic view...
yup. AI programming isn't a whoodoo voodo thing only guru's can do. It's
just making your computer opponents aware of the game and their options,
and giving them some way of choosing their options.
> > If you ask 5 risk players how to play, you'll get at least 6 "optimal"
> > strategies.
> ----------8<----------
> strategy stuff deleted
> -------->8------------
>
> > The "best" way to create computer AI is to make the game playable by human
> > players, then play about 20 games with human players and have the computer
> > keep track of every move of every player. You then can "teach" the
> > computer to play like you do.
>
> And who says you're so good? (Don't take it personally, but I'm not
> convinced)
It doesn't matter if you're good or not. You know the game, you know the
rules, you give your alter ego a goal and a strategy, then watch him play
and advise him when he does something stupid. It's really easy to teach a
computer player to play better than you do. You won't always follow your
agenda to your best interest, you'll sometimes miss an opportunity, you'll
sometimes get desperate and do something stupid. The computer is more
disciplined. You give it your decision priority list and it will follow
it until it wins or loses.
> ----------8<----------
> more stuff deleted
> -------->8------------
>
> The normal aproach to board-game AI's is the one (normally) used for chess:
>
> Max-Min algorithm
> =================
>
> Make a function to give each board-situation a value (score if you like).
>
> 1. Make a tree of all possible moves (except suicidal ones), and
> evaluate them (the resulting board), and cut away the most stupid
> moves. (lowest score)
In chess you do this dynamically after the opening moves. I designed a
nifty chess program for Interplay that analyzed your moves, as well as for
the computer or modem opponent and warned you if you or they did something
stupid. It told you why the opponent was doing what he did and what
advantage or disadvantage the move gave him.
<snip>
> It's only in real-time games or games with *enormous* branching that really
> require something as obscure and intagible as "tactics and strategy".
> For Risk, I'd write the valuation function to valuate for any player,
> since *each* player is trying to *max* his own score. (If there were
> trying to *minimize* *your* score, like chess AI's, they'd all gang up
> on you! 
)
Strategy is ALWAYS important. Even in Chess, you have agendas, you have a
basic strategy. A game situation is dynamic, sometimes the table
generated "optimal" move isn't the "right" move for your character this
time. Sometimes you let the queen do her thing while you move your pieces
around. The whole point in doing computer AI for something like RISK is
to give multiple opponents multiple personalitiess, multiple game play
agendas and options. You need to give them some room to work around the
rules they play by. If they always do what you expect, the game isn't
fun, you always win or you always lose.
The various "players" may or may not try to maximize their score all of
the time. They may choose to kick your wimpy butt out of their area of
influence because you annoy them rather than do a move into africa that
will give them more points. My AI's would taunt you at that point =)
Another example. In StarTrek: Judgment Rites, when you were in
space combat against the Klingons, their basic strategy was to turn their
ships toward you and shoot at you no matter where you were. Their AI was
simple "kill the target. Stay out of their sites, cloak if possible."
They were pretty easy to destroy: get one in your sites and do whatever it
did and keep firing. If you faced 2 or three of them, as long as you kept
one in your sights and fired, the others would have to keep turning and
moving to try and hit you. If you kept moving, they couldn't target you
easily and you could blow up the ships one by one if you were good.
In StarFleet Academy, the Kilngon AI is slightly different. When you face
multiple klingons, they have multple attack strategies that they use when
necessary. They form up together moving away from you, when you pursue,
one or more breaks formation and peels off away, around, behind your ship
then blasts the bejeebers out of you, then they regroup and depending on
your damage\ability to fight, they do something else. They like to
disable you then gang up on you for the kill. They also learn your
tactics as you face them in combat and can anticipate your moves. As you
play they get harder to defeat because they KNOW you better.
One way is hard and repetitive once you get the hang of it, the other is
manical and constantly challenging.
The more varied your AI the more interesting your game.
> Hope it helps... I'll try to get some work in on the tree.e...
>
> (Hey! Here's another use for trees!)
I build landscapes with nice trees. =)
Michael Packard
Lord Generic Productions
lgp at exo.com http://exo.com/~lgp
A Crash Course in Game Design and Production
http://exo.com/~lgp/euphoria
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