Today, the topic on my mind is online roleplaying games, what is popularly called a MU*. A MU* is a text-based site on any of a number of code bases, related to MUSH - Multi-User Shared Hallucination (I think a MUSH is a MU*, but a MU* isn't always a MUSH? This is computer guts stuff and I'm not going to get too worked up about it) and more distantly to MUD - Multi-User Dungeon, which is basically a glorified hack and slash game with minimal or no character interaction.
Because character interaction is what roleplaying boils down to: writing out your character's actions (and sometimes a little bit of thought), firing them out into the void, and getting the response from another player and character who could be half a world away. I started out in fandom - games that emulate an author's world, though I've always gravitated towards those that avoid / don't allow the use of his/her characters - and moved into original settings, where I had a lot more fun.
There are aspects of these roleplaying games that have helped my writing, I think. For instance, you get immediate feedback on clarity, whether it be an out-of-character question / confusion or the other character misreading. When trouble arises in the game world, it stretches your plot / problem-solving skills as other people come up with solutions you would never think of. (Or conclusions ... I've had moments of sitting at the screen, staring, and wondering how in the world ... ?)
A good portion of what occurs on a game is day-to-day rather than strict pursuance of plot, so it's great for developing side aspects of character building. And since this kind of writing means you're showing more of the "mundane" side of the character that might be glossed over in a novel and missed entirely in a short story, it encourages you not to immediately, blindly reach for your own preferences and foibles. Also, let's face it: at the most basic level, it's practice.
There are aspects to roleplaying games that can negatively affect writing if not watched, but I think it's overall positive, and it's a better downtime hobby than shooting aliens. ... I mean virtually. Stop looking at me like that.