I highly recommend you give the Exile series from Spiderweb Software a chance if you haven't. It's a bit dated graphically, but it's engine has been kept up and there's some new Avadon series as well. It's hands down some of the best storytelling and I've easily played hundreds of hours. I've definitely played from night to morning without realizing it more than a few times.
I really liked the older games as well (a long, long time ago). I still remember the "shareware canyon" that was impassible without buying the game in full. Fond memories!
