Second half of year 2. Have been playing the same sandbox game since I got into KSP around 0.20 and am getting close to 500 hours under the belt. Got about 65-70 vessels in use not counting EVAs or flags. Even ignoring one-off landers and satellites, that figure is still around 45-50. Every time I wait for a launch window I find myself building more craft and coming up with new missions and thus I seldom time warp more than a few hours at a time. I'm currently spending the time before the next launch windows to Eeloo, Jool, and Dres (about 10-20 days) rotating crews in the Kerbin system as well as building, testing, and readying all the vessels for those launch windows. Here's the kicker: I've still got all of the Joolian system and Eeloo to explore. Haven't made planetfall on Moho or Gilly yet. At this rate, I'd expect to plow another 500 hours into the save before being "done".