Back in the 90's, I used to use MS Flight Sim, (2 maybe?) and SubLogic's Flight Assignment: ATP. I saw MS Space Simulator on the shelf at Babbage's one day (does anyone else remember that store?) but it required a better computer than my 386, and being a poor college student, I put it off for a future day, fully expecting that by the time I had a real job, there would be plenty of space sims, with lots of cool graphics and features. I didn't know at the time that computer flight sims were already dying in the marketplace. Sure enough, MS Space Sim vanished, and I put my interest aside to get on with my career.
Fast forward to early 2005, and I decide to google MS Space Sim and see if it's downloadable like so much other abandonware. I actually found it and DL'd it, but I couldn't get it to work right. So I followed the link to Orbiter, which said "free" in it somewhere, and as the bounty hunter in the Firefly episode Objects in Space says at the end of the episode, "Well, here I am".