Yes games are very addictive. On an average I have seen most people play games for more than five hours a day and that they can't do anything while they are playing a match, for instance, until they can go eat, go to the bathroom, leave the house. Their lives revolve around gaming and competing against others to level up or improve their skills depending on the genre of game they are playing.
For my brothers are both CSS players and will play the game from 3:30pm till 11:00pm everyday unless my older brother turns the net on at 1pm and will still play till 11pm. If they ever receive 'ping' from the net downloading too much at one time they will both seriously complain till their ping has returned to normal. It seems strange to me that they will complain so much about me using the internet the same time they are playing because they don't even pay for the service so it isn't theirs.
So I would say Yes gaming is addictive and its not to a certain degree. Its more about the players own state of mind. See for some gamers they tend to get into the game way too much and its very much apart of his/her life. Where as for some its more about something to do when one is bored in their spare time and are able to control their game playing time more.