Copy protection is a method of making it difficult or impractical for people to make illegal or unauthorized copies of a game. This is usually only of concern with commercial games or shareware games, where pirate copies potentially reduce the authors' profits substantially.
By contrast, IF hobbyists usually don't bother with copy protection at all. Sometimes a user license is included with the game, sometimes not, and the authors trust that the public will do the right thing and not screw the authors over too much by ignoring their wishes.
The most common form of copy protection requires shipping a legitimate copy of the game with something non-electronic, a tangible something called a feelie that also contains information necessary to complete the game. (Not all feelies are instances of copy protection; some feelies are just fun items that add value to the purchase.)
Feelies that contain copy protection information should be difficult or annoying to copy, to act as a disincentive to copying. Examples include:
- Books or booklets. A person is less likely to photocopy a 50-page book than one or two pages.
- Color printing. Light blue ink didn't photocopy at all on older black-and-white photocopiers. Red ink on dark paper might photocopy as solid black. Now that color photocopiers (and digital cameras) are more commonplace, this scheme isn't so useful.
- Non-ASCII character glyphs. Weird shapes can't be typed directly in e-mails; one would have to describe them or take a picture of them or come up with an ASCII encoding of them to get around it.
- Lots of numbers. People hate typing out long lists of numbers and chances are good that the copier will make mistakes.
- Code wheels. How badly do you want to disassemble your code wheel, photocopy the parts, and then get the other person to reprint the parts and reassemble the code wheel at the other end?
- Hiding in plain sight. If the feelie doesn't look like it contains copy protection, people might not realize the feelie is important. Or the feelie could contain lots of information, and it's not obvious what parts are significant.
Shareware publishers might opt simply to make the copy protection info a separate purchase. That is, the main game program is released to the public, but to finish the game, you'll have to send a small payment to the author to get the copy protection info mailed (or e-mailed) back to you.
Examples of copy protection methods
Games published by Infocom:
- Ballyhoo included an booklet that could be mostly ignored except for an ad for radio station WPDL that includes its AM radio frequency.
- Hollywood Hijinx included a photo of Uncle Buddy with a handwritten poem on the back which contained a hidden clue on how to unlock the front door.
- Leather Goddesses of Phobos included both a catacombs map and a comic book, both of which were needed to navigate the game's catacombs maze.
- The Lurking Horror included a student ID card; the player needs to know his or her ID and password to use the school's computers.
- A Mind Forever Voyaging included a code wheel that had to be consulted every time Perry wanted to enter simulation mode. Unhappily, the code wheel included spots of color without naming them, while the game, of course, refered to the colors solely by name.
- Sherlock: The Riddle of the Crown Jewels included a two-sided newspaper page, filled with articles. It was hardly obvious what part of the newspaper contained the information necessary for finishing the game.
- Sorcerer included an infotater feelie that describes twelve creatures and associates them with arbitrary color codes, which the PC must reproduce to unlock a trunk early in the game.
- Stationfall included long lists of numerical coordinates from which the player had to consult to navigate the spaceship to its destination.
- Zork Zero included The Flathead Calendar 883 feelie, a calendar booklet containing mini-biographies of the Twelve Flatheads plus interesting trivia about Zork. Illustrations depicted the Flatheads with the objects most associated with them. A careful perusal of the text, however, was necessary to learn less obvious facts, such as how to find the secret wing of Dimwit's castle, how to summon Antharian cave-dwelling witches, where Frank Lloyd Flathead's office was, and how to avoid losing a game of Double Fanucci.