OtherSpace Interactive SF Saga
It's tough to write anything else about this MUSH that hasn't already been discussed in any of the previous reviews, so I'll just have to settle for emphasising just how great it is. It's great.
The idea of an original theme worried me at first - in other games these tend to be either too overblown and melodramatic or just boring and not actually not that original at all. OtherSpace in none of these things - imaginative, immersive and atmospheric are just a few words I would use to describe the theme.
The staff and players are incredibly newbie-friendly, and there are a multitude of races and professions to choose from. The RP is of a high standard and, more importantly, enjoyable. I'll stop now before I start to repeat other reviewers - just to state that what they say about OS is true.