I just dropped out of a Star Trek game, not because I did not like the premise or had a falling out with one of the players. It was not due to a bad plot element or the GM including marines in the game.
No, it was due to the fact the GM disappeared.
This is an issue I have seen over the years with both GMs and player alike. A person gets involved in a game and for one reason or another stops communicating altogether. In this day and age of easy access to the internet I do not see any excuse for this. Twenty years ago, maybe. But internet access is available in most libraries as well as FedEx Office locations. You might have access to the internet at work, or your friends probably have access to the internet, even your parents! That does not include internet access through many phones. When guys stationed in the field in Afghanistan and Iraq can check their e-mails, I find it hard to believe that anyone living in a more civilized region can't at least once in a while.
I am not talking about running a game through alternative internet sources, but if you are having trouble with your primary internet source then it behooves you as a player or a GM to at least let people know what is going on. It is the polite, responsible thing to do.
"But Tom," you say, "My father died, I am not feeling much like chatting online." Bull. If a loved one died or was put in the hospital you would notify work, wouldn't you? You would notify your friends, right? If you had social engagements you would contact those involved so you would cancel or reschedule, correct? There is absolutely no difference here. Just because you have not met any of your players face-to-face it does not makes them any less important. Again, I am not talking about running a game or participating, just let people know what is going on so they don't worry.
And let's say you have grown bored with a game and no longer wish to play or run it. What is the harm in letting players know how you feel? Not letting your players know, leaving them in the dark could conceivably harm your chances of running a game later on down the line if you develop a reputation as a flake. Just flat-out disappearing as a player could hurt your chances of being picked up for a game later on down the line for the same reason. It makes you look like someone who views players as disposable, not important.
So please, if for one reason or another you are unable to participate in a game, do the proper, adult thing and don't leave people in the dark.