A 1 or 2 player version of the famous board game
BEGINNING THE GAME: The program requires a
minimum 24K RAM with 1 or 2 joysticks, has single and two player
options and is compatible with both 400/800 and XL/XE machines. XE
owners, however, may like to boost the colour saturation control on
their TV for best effect.
After typing and saving the listing turn up the TV
sound and RUN the program to initialise it. When the title screen
appears enter each player's name (followed by the RETURN key), up to
nine letters will be accepted. If you wish to play the computer
enter ATARI for one of the sides or, for a demo of the program, you
can even have the computer play itself by entering its name for both
sides!
The blue player uses a joystick plugged into port
1, the green player uses one in port 2. If you only have one
joystick and wish to run the two player version change the 'PLR' in
line 400 to '0'- both players then use the same joystick plugged
into port 1.
Once the board has been displayed press the
trigger to begin.
OBJECTIVE: The objective is to remove all
your tiles from the board before your opponent and, additionally, to
attempt to manoeuvre his pieces to your advantage.
Tiles are moved around the board according to the
throw of the dice, obeying certain rules. Blue moves clockwise in
ascending fashion; green moves anti-clockwise and descends the pegs.
Once all your tiles occupy the appropriately coloured pegs in the
last six positions you may begin to move off the board.
RULES: A player cannot move his tile onto a
peg which holds more than one of his opponent's pieces, nor can more
than five tiles occupy any one peg. A solitary tile is vulnerable to
attack and will be displaced onto the bar if hit by an opposing
tile. In such a case a player must move his tile(s) back onto the
board before any other move can be made - if unable to do so because
of existing tile placements he forfeits his turn. No piece may be
moved off the board by a player unless all his remaining tiles
occupy the colour-coded pegs. Finally, providing moves are possible
which do not infringe these rules, both dice must be used each turn
- they can, however, be used in either order.
PLAYING THE DICE: The computer decides who
will commence the game and throws the dice automatically at each
turn. A player then has the option of moving two tiles by the value
shown on each die (he could also move the same tile twice) or of
moving one tile by the sum of the dice. For example, suppose a 3 and
a 5 are thrown at the start of the game. You could move a tile from
peg 13 to peg 10 (if you are green) and another from peg 24 to peg
19. You could, alternatively, opt to move a single tile from, say,
peg 11 to peg 3 or the same tile from peg 24 to peg 16.
If you receive a double, each die is played twice.
For example, a double 5 enables you to move 4 tiles 5 places each or
2 tiles by 10 places. You must, however, treat the dice as pairs -
in other words you cannot play the 5 followed by the 10 followed by
another 5.
Before returning control to you the computer will
check for possible moves. If you cannot move according to the above
rules you will be informed of this and play will be pass to your
opponent.
MOVING THE CURSOR AND TILES: At the start
of a game bring the cursor onto the screen by moving the appropriate
joystick to the left. Then move the joystick in the required
direction (except diagonally) to select the peg from which you wish
to move a tile. Press the trigger to register your selection. If
valid the marker below the board will move right asking for a
destination for the tile. This you register in the same manner. If
the move would be an invalid one both your peg selections are
cancelled and you must make new entries. If you decide against a
move after inputting a source value simply enter an invalid
destination and start again. Your move will then take place with the
used die, or dice, reducing in luminosity to highlight remaining
choices.
If you are 'on the bar' the computer automatically
registers this as the start point and you are only required to enter
a destination. For example, with a 3 and a 5 thrown the blue player
could enter the board (if valid) via pegs 3 or 5. The green player's
corresponding pegs would be 22 or 20. To move off the board
(numerically equal to '25' for blue and '0' for green) select the
tile then position the cursor until the arrow symbol appears in the
'destination' box. Press the trigger to initiate the move.
During a game, providing you have control of the
cursor, you may restart via the title screen by pressing the 'Start'
key. Pressing 'Select' or 'Option' returns you to BASIC.
STRATEGY: This is an important feature of
the game. You must decide if and when to deposit your opponent onto
the bar remembering that he will re-enter via your inner quadrant in
most cases. Figure out which are the safe moves to make, when to
gamble and how to block your opponent's advances. As you manoeuvre
your pieces around the board attempt to deposit your opponent on the
bar when safe to do so but reduce his opportunities to re-enter with
strategically placed tiles. At the close of the game points are
scored according to the number and position of all remaining tiles,
greater points being given for those furthest from the opponent's
inner quadrant.
WINNER: The winner's performance is
evaluated in three ways in order to offer different 'goals' when
playing against the computer. Tile advantage is simply the number of
your opponent's pieces remaining on the board at the end of a game.
Total moves is self-evident - the lower the value the more effective
has been your strategy. The score is based on the number and
position of remaining tiles; high scores result from keeping your
opponent away from his inner quadrant. As is usual with games
involving dice, luck does play its part but certainly not to the
exclusion of a good strategic approach.
GAME DESIGN
It was decided at the outset to use a character-mapped screen for
the board and Antic 4 was chosen since this gives 5 colours at a
resolution equivalent to BASIC's mode 7.5. It does, of course,
require some effort in redesigning the character set. The number
characters were additionally altered for greater prominence but they
reside on Gr.0 lines above and below the board itself. DLI's were
incorporated to permit multiple use of Players and colour registers.
The dice illusion is achieved by overprinting two players with
appropriate substrings from DICE$. The cursor is pulsed via a simple
VBI but, because it is the same player as used for one of the dice,
its position and priority must be adjusted in one of the DLI's. An
expanded display results from the use of Players to extend the
horizontal boundaries of the board and the inclusion of Graphics 1
and 2 lines below the board which gives prominence to the displayed
information.
THE JOYSTICK ROUTINE was then added,
positioning this some way in to the BASIC listing in order to give a
built-in delay to cursor movement. Any routine positioned near the
start of a listing will operate more quickly than if located at the
end - hence the positioning of 'frequently used subroutines' in
lines 10 to 100 in this game.
TILE MOVEMENT AND GAME CONTROL came next using a simple array
to keep track of players' tiles and the program was extensively
play-tested before adding m/code subroutines to smooth out movement
of the tiles. In order to compact the program a series of variables
was incorporated to make one master routine in the main loop operate
for both players. Since the green player operates in a numerically
descending manner this involved an inversion of blue-player logic.
THE COMMON INTRO/EXIT SCREEN uses a mixed-mode display list
with title displayed in Antic 5. Careful choice of foreground
colours whilst pulsing the background in a VBI results in good
legibility of the standard character set.
COMPUTER LOGIC (for the single player version) was kept
fairly simple in order to restrict 'thinking time' but it
nevertheless plays fairly intelligently and it isn't a simple matter
of achieving high scores. Routines were placed near the start of the
program for optimum processing speed, their addition significantly
reduced cursor speed as described earlier.
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