Agent USA is a geography enhancement game that centers around a character that travels by train to different U.S. cities. The object of the game is to find the "FuzzBomb" which turns ordinary people into "FuzzBodies". You plant crystals which regenerate into newer crystals, and when you build up 100 of them and touch the FuzzBomb, the nation is saved!
Part of the copy-protection routine for the PC port of Agent USA relied on a clever attempt to socially-engineer crackers: The program attempted to see if sector 0 was writable, and if so, proceeded to write junk all over it, rendering the diskette unbootable. Why is this clever? Because the original factory diskette was write-protected (in fact, it lacked a notch completely) and the check would always fail on a factory original.
May 1985 (Issue 1) - #36 'It's the Zzap! 64 Top 64!'