At least one of the U.S. 3.5" floppy disk releases contained an interesting form of copy protection. In addition to the game randomly asking you on game start-up to insert the 3.5" floppy install disk to verify you have a legitimate copy, the install disk itself was "defective by design". Portions of the disk have an invalid file and/or cluster structure. Running the disk through a disk checking program such as Windows Scandisk will show these errors, but they're all "by design", so it's important that you don't correct them using such a program. Even if you copied the disk using specialized disk copying programs, more often than not, the copy will not be accepted by the game when it asks you to insert the install disk.
