Game Development Reference
the two. Although a book of moves may lend itself to a rule-based imple-
mentation, the focus of this chapter is on hybrid AI in which the topic of moves
supplements a more general AI system, which need not be rule based. Our hybrid
AI can ''order from the menu'' using the topic of moves or it can ''send requests
to the kitchen'' using the general AI. It is easy to think of the topic as a set of
narrowly focused, highly effective responses to specific circumstances, but they
need not be that restrictive; the topic can also contain typical moves that the
player will expect to see. We will look at some broader, complex applications
before looking in depth at how a book of moves might apply to more accessible
AI. That said, rule-based systems and a book of moves are conceptually quite
close, and fine distinctions between them may not be terribly enlightening.
Composers today might consider Mozart unfair competition from beyond the
grave, but the truth is that anyone who can read music has full access to Mozart's
genius. Similarly, with a book of moves, game AI need not compute genius
moves; it just has to be able to use them appropriately. If programmers can
implement the AI equivalent to sheet music, they can then exploit any form of
brilliant play they can codify. Moves tend to be specialized; Mozart's music might
not be appropriate to the instruments of a rock band. Good moves need not
always be hard to find.
Imagine an in-game cut scene for the aftermath of a great battle. On one side, we
see the local religious authority give the words for the living and the dead. On the
other side, we see a similar figure giving similar but different appropriate words.
There is no reason for the AI programmer to write either set of words; found in
the back of countless hymnals and religious topics are brilliant but relatively
unknown writings, perfectly suitable for funerals. The selection of good words
throughout the ages is rather quite rich, translation issues aside. The really old
ones tend not to be familiar, making them novel when reused. As an added
bonus, the copyrights on the oldest works have expired.
A similar case can be made for battle speeches, though more care must be taken:
''And gentlemen in England, now abed,
Shall think themselves accursed they were not here,
And hold their manhoods cheap whiles any speaks
That fought with us upon Saint Crispin's day.''