In this chapter, we have presented a survey of literature relevant to our work in this thesis.
Firstly we established all terminology relevant to discussing games as a scientific discipline,
then AI concepts with a specific focus upon MCTS. We then moved on to literature re-
lating to entertaining play experiences, and finally provided an overview of Data Mining
Game Domains and Experimentation
Software
3.1
Game Domains
The following Game Domains were selected for experimentation.
3.1.1
Lords of War
Lords Of War1is a two-player strategic card game by publisher Black Box Games. A board
is used for card placement, and the relative positions of the cards on the board are the main
strategic interest. A player wins when they eliminate twenty of an opponent’s cards, or they
eliminate four of their opponent’s Command Cards. Command cards are significantly more
powerful than other cards, but placing them onto the board carries a risk that they may be
eliminated.
The game board is 7 × 6 squares each of which can hold a single card. Cards have be-
tween 0 and 8 attacks, each with a strength value, and a directionality towards an orthogonal
or diagonally adjacent square (see figure 3.1). Attacks from multiple cards can be combined
Figure 3.1: Bestial Raptor, an example card from the Lords of War game.
tacks which can eliminate (or contribute towards the elimination) of opponent’s cards which
are not adjacent. In regular play, cards can only be placed so as to attack enemy cards, how-
ever Support Cards also have additional placement rules allowing them to be placed next to
friendly cards instead of attacking enemy cards.
On each player’s turn, they are required to place exactly one card, then process combat to
identify and remove eliminated cards, then they have a choice of either drawing a new card
from their deck, or retreating a friendly unthreatened card from the board. The complete
rules of Lords of War appear in Appendix C.
A normal game rarely extends beyond 50 turns, as most moves (particularly strong
moves) result in a capture. Once an average human player has made 25 moves, they have
probably captured more than 20 cards, and thus the game would have completed. Of course
the games can end much sooner if command cards are placed carelessly or last much longer
if players play cautiously. Games with MCTS agents last on average between 30 and 60
length, but normally last between 50 and 120 turns. Our experience with Lords of War
has revealed that it commonly has a mid-game branching factor of 25-50, making move
selection challenging.
Lords of War was chosen for research as it represents a complex game in which players
can adopt a number of different strategies and play styles, which provides a wide range of
behaviour for us to analyse.
3.1.2
Android: Netrunner
Android: Netrunneris a two-player strategy card game published by Fantasy Flight Games2,
which includes elements of bluffing and deception. Netrunner is similar to other popu-
lar card games such as Magic:The Gathering, and is described as an LCG (Living Card
Game [55]).
During a standard match of Netrunner, opponents do not have access to the content of
their opponents deck. Access to such information would provide a substantial advantage
to a player, as they would both be able to predict their opponent’s likely strategy, and also
determine which strategies they are poorly defended against.
Due to the nature of the game, the content of an opponent’s deck is critical strategy
information, and a player who is able to accurately model their opponent’s deck is at a
substantial advantage. There are currently more than 600 cards released for Netrunner, so
accurately modelling a deck is a significant challenge. The combination of the wide number
of choices, plus the complex and specific rules for which cards may be included in decks
makes Netrunner deck construction a highly intricate process.
Netrunner has a well documented rules structure for deck building. Every Netrunner
a Side, an amount of influence and a Faction. There are exactly 2 sides (named Runner
and Corp), and each card in Netrunner is associated with one side and cannot be included
in decks associated with the other side. Identities which are from the corp side must also
include a specific number of agenda points, which are provided corp cards (the specifics of
agenda points are not relevant to this work, other than to recognise that there is a required
number of agenda points for some decks to include, which presents an additional restriction
upon decks.) All non-identity cards also have a Faction and a Influence Cost, the latter of
which describes the amount of influence which must be paid to include the card in a deck
which contains an identity of a different faction. The complete rules of NetRunner appear
in Appendix D.
Netrunner was chosen as a target for research due to the large amounts of imperfect
information, and that bluffing and deception are integral to play, meaning that the content of
an opponent deck is of very high importance.