RNG

RNG, aka Random Number Generator.

RNG is basically the luck factor in video games. Whenever something needs to be randomized, a random number generator is used to generate a semi-random value. This value is then used in functions in the game code that results in something happening inside the game world. These events may be subtle, like determining how an enemy will move, or the starting point in a cycle of a moving platform.

Since random numbers are produced by algorithms, this specific nature makes the generated value predictable and manipulable in certain situations. For example, certain algorithms will use the game console's system clock. So resetting the clock to a specific time may allow you to manipulate the resulting value into always resulting in the same value.