Marbles
Stephen Stout
Act quickly—and don't panic—in this clever arcade-style game for the Atari, Commodore 64, Amiga, Apple II, and IBM PC/PCjr and compatibles. The Atari, 64, and Amiga versions each require a joystick. The Apple version requires paddles. The IBM PC/PCjr version requires BASICA or GW-BASIC and a color/graphics adapter for the PC and compatibles, and Cartridge BASIC for the PCjr. The Apple version runs under DOS 3.3 or ProDOS.
In two weeks the Statewide Marbles Championship will be held in Localsville. You've been practicing for nearly a year, and now, at the last minute, you find you've lost your favorite marble. You're going to have to collect every marble you can to find one as special as the one you lost.
"Marbles" is a hypnotic arcade-style game in which you try to catch marbles in a bucket. Originally written for the Atari eight-bit computer series, we have added versions for the Commodore 64, PC/PCjr and compatibles, Apple, and Amiga computers. Each version of the game is unique, so be sure to read the instructions for your computer for the details of the game.
Atari 400, 800, XL, And XE Version
The Atari version of Marbles (Program 1) is written entirely in BASIC. Type it in and save it to tape or disk. The program listing contains many special graphics characters. Refer to the "Guide To Typing In Programs" article elsewhere in this issue for details on typing these characters. To play the game, simply load and run the program.
Use a joystick plugged into port 1 to control the buckets. Press fire to start the game. The marbles fall, one at a time, down the pipes. When a marble comes to an intersection, it may go in any direction.
There are seven screens in this version of the game. Your task is to catch 20 marbles on each screen without dropping even one. If you do drop a marble, you must start over with the same screen. To further complicate matters, you must catch red marbles only in the red bucket and blue marbles only in the blue bucket. Catching a marble in the wrong bucket counts as a miss.
The game ends when you've managed to catch all the marbles on all seven screens.
Commodore 64 Version
This version of Marbles (Program 2) is written in machine language, so you'll need to type it in using the 64 version of "MLX", the machine language entry program found elsewhere in this issue. Be sure you're familiar with MLX before you begin typing in Marbles. When MLX asks for starting and ending addresses, respond with the following:
Starting address: 0801 Ending address: 1500
Type in the data, and be sure to save a copy to tape or disk before leaving MLX. Although the program is in machine language, it can be loaded and run like a BASIC program. When you're ready to play the game, simply load it and type RUN.
Use a joystick plugged into port 2 to control a bucket at the bottom of the screen. The marbles in this game follow the arrows that occupy the intersections of the pipes. Press fire to change the direction in which the arrows point. (The arrows move clockwise.)
A feature unique to this version of the game is the gremlin, which is created whenever two different colored marbles collide. (Both marbles are destroyed when the gremlin is created.) If a gremlin collides with a marble, both are destroyed.
As gremlins travel around the maze, they sometimes change the direction of the arrows they cross.
You advance to the next screen (there are a total of nine) by scoring 1000 points. Each ball you catch is worth five points. This value increases whenever a gremlin drops through. If you catch a gremlin, the ball value goes back to five. Each screen allows you to miss a certain number of marbles (displayed on the screen as passes). If you drop any more than the limit, the game ends.
Apple II Version
Marbles for the Apple (Program 3) works on any Apple II-series computer, under either DOS 3.3 or ProDOS. A pair of paddles is required. Because the program is written entirely in machine language, you'll need to type it in using the Apple version of "MLX." When MLX asks for a starting and an ending address, respond with these values:
STARTING ADDRESS? 2000 ENDING ADDRESS? 2A17
Type in the data, and be sure to save a copy to disk before leaving MLX. When you're ready to play Marbles, enter BRUN filename, where filename is the name you used for the Marbles program.
This version of Marbles can be played as either a one- or two-player game. Exactly 40 marbles drop on each level. To make it to the next level, you must catch at least 20 of the marbles. If you do not advance to the next level, the game ends. Use the paddle to move the bucket. When you play the two-player game, players alternate turns. When one fails to advance, the other keeps playing.
When marbles drop into the maze, they appear as asterisks (<+>*). When an asterisk travels over a dot, it turns into an at sign (@) and the dot disappears. You get points only for the latter type of marbles—one point for each dot the marble travels over. Each intersection has an arrow that determines the direction in which the marbles travel. Press the paddle button to change the direction of all the arrows on the screen. The arrows move clockwise. (Note: On Apple II and II+ models, alphabetic characters will appear in place of the arrows and buckets. This does not affect the operation of the game.)
Press the space bar to pause the game. Press it again to resume play.
Amiga Version
The Amiga version of Marbles (Program 4) is written in BASIC. Type it in and save it to disk. To play the game, simply load and run the program.
To play Marbles, you must have a Workbench 1.1 disk or the most recent version of Workbench 1.2. The first release of 1.2 does not properly allocate sprites 6 and 7.
A joystick plugged into port 1 controls the buckets at the bottom of the screen. You must catch the red marbles in the red bucket and the blue marbles in the blue bucket. The arrows at the intersections of the pipes control the flow of marbles. Press the fire button to change the direction of all the arrows on the screen. The arrows move counterclockwise.
This version of Marbles can be played by up to five players. The one-player game starts with three marbles on the screen at once. After every ten points, another marble is added until there are six marbles on the screen at once. The game ends when 40 marbles have been caught. Your score is the percentage of marbles you caught.
In the multiplayer game (two to five players), all contestants play the same level. After each has had a turn, the player with the lowest score is dropped from the game. When only one player remains, he or she is declared the winner. If two or more players tie for low score, the level is played again.
IBM PC/PCjr Version
This version of the game (Program 5) has the same rules as the Amiga version (described above), but there is only one bucket. However, you must change the color of the bucket to match the color of the ball you're trying to catch. Use the cursor keys to move the bucket left and right. The cursor-up key changes the color of the bucket. Press the space bar to change the directions of all the arrows on the screen.