Actually, the original version of Oubliette (circa 1977) had secret doors. It also required you to carry torches, and if they all ran out, you had to stumble around in complete darkness (although there was a magic spell to produce light). Also when you died, you had one chance to make raise. If it failed, you were permanently dead and there were no portal gems, so you simply had to start over.
In general, the game was a good deal harder than this one. I don't believe that I EVER had a character over level 12 or so. Of course we were always taking crazy chances and getting our whole party wiped out, but that is what made it fun for us.
As I said before, if I were to create a version 2, it would go back to the multiplayer roots. Unfortunately, I don't think I could interest enough players to make a multiplayer game viable, even if I were to offer it for free.