Dungeon Master (Amiga)
Dungeon Master is a real-time RPG, originally released for the Atari ST.
Both the Amiga and Atari ST versions of the game use a media check to confirm if the game is original. Specifically, certain sectors on the disk use fuzzy bits, which likely change each time they are read (and, crucially, require expensive professional duplication hardware to copy while preserving their fuzzy-ness). If the game detects the fuzzy bits give different results each time they're read, then the game works without issue. An initial check locks the game at one of the title screens, thus a casual disk copy (or casual emulation attempt) will stop before you can enter the dungeon.
Additional anti-piracy checks exist in the code, including further fuzzy bit sector reading, checksums, code hidden as images in GRAPHICS.DAT, and other fun tricks intended to slow down and frustrate crackers. These respond with a delay-action effect, which result in one of the following:
- Disk insert prompts, even when the disk is already in the drive.
- Soon after a level change, timed gameplay updates stop. This causes monsters to simply freeze in their position, doors being unable to open and close, thrown items and launched spells remaining in mid air, and cloud effects from monsters or spells not clearing, and character's action cooldowns not clearing. This will eventually lead to a "System Error 60" due to some buffer overflow. (This check sometimes backfires, due to the frozen monsters potentially providing an advantage to the player, allowing them to get through a tough situation and save before things explode...)
- All PCs being insta-killed. Being killed in this fashion deactivates the ability to load a saved game, thus the player needs to reboot in order to continue from the last save.
It is still possible to complete the game if you save progress frequently. These checks only hinder progress rather than making the game impossible. Additionally, creative exploitation of the copy protection could be used as a sequence break (but inefficient compared to completing the game normally) by negating some triggers that would close a door.
The v3.6 version, released by Psygnosis, allows drinking directly from a fountain (rather than using a waterskin or flask), and also allows clicking on walls to check if they're real (as opposed to manually bumping into each wall.)
One group of crackers (led by The Driver/Dytec) released their v3.6, claiming that they didn't find the above anti-piracy countermeasures after two hours of playtesting.