Realism

Realism is a qualitative component of games that describes the degree of accuracy to which a game simulates phenomona that exist in reality. This can include many things from the rate of fall an object experiences in a virtual Earth to the accuracy of events occuring in a game based on the capture of Berlin in 1945. Generally speaking, realism can be defined on a linear scale, with arcade games being at one end and simulations being at the other. Arcade games aim to be fun with blatant disregard for Newton's laws, whilst simulations often allow the player to apply real world skills such as room clearing tactics or advanced flight manoeuvres to their experience. Realism is rather progressive, a game that was realistic a few generations ago may later be viewed as arcade by comparison to those that have superceded it. 

A common discussion among many gaming fora is the preference of arcade or realism, at the end of the day it is all down to personal taste. A common argument against realism is that it is tedious and unnecessary as many gamers play to escape reality. Contrary to this realism proponants argue that realistic games allow them to achieve objectives they could never do in reality for moral or fiscal reasons, such as flying aircraft or shooting people. Realistic games can also be very rewarding because of the incredibly steep learning curves that deter many would be players.