Random sampling involves picking samples from the population at random. As the population here consists of only 5000 video games this is not very difficult to do and there is no error introduced due the nature in which the sampling is done.
A random number can be used to choose numbers that fall in the range 0-5000. Random number generators are software programs that can use any value that is non-deterministic and use it to arrive at a number. For example, the program could use the words of any random page chosen from a book and determine a number using the letters of each word with the help of other parameters that are also randomly identified.
The output of the random number generator gives the video games that form part of the chosen sample.