Copy protection system
Stunts and 4D Sports Driving include a form of copy protection which is usually called "doc check" and was common in the early 1990's. Back then, it was was not imaginable that creating a hardcopy or even an OCR scan of a paper document would be achievable for everyone only a few years later. Each time after running the original executable file, player must enter a specific word from game manual before being allowed to race. If the player fails to complete the phrase three times, the race will still load. However, the player is informed that the car's security system is not disabled and the car crashes. Once the player entered the correct word, the questions will not appear again for the current session.
In Stunts, the player is always shown a part of a sentence where one word, the answer, has to be entered into a gap and is given by the page, line, and word number in the manual. There are only 20 possible questions which, due to the surrounding phrases, usually can be entered by heart after some time or even be guessed. In 4D Sports Driving, the protection is more complicated. The word to enter is given by page, line, column, and word number in the manual and no surrunding phrases are provided as clue. Also, there are 127 possible questions, which is a lot more than in Stunts.