I have played for several hours now and have been trying to look thoroughly so that I find all quests. Still I am unable to find some quests like unicorn and mika the witch. I have been roaming every corner of Land of Ardyl with no unicorns or petrified people. Is there a problem in installation or am I just missing something?
There are 22 total quests, but each time you start a game, only 8 of them are selected and made available for that playthrough, so you can't really finish all quests in a single playthrough. See this guide for more information: https://gamefaqs.gamespot.com/pc/197057-darkstone/faqs/2545
Originally played this on the Playstation. It's missing one quest from the quest pool, as it requires two players to complete and the PS1 version is limited to only one character. There are some other changes to the town (no training area) and some of the areas are maybe slightly smaller or minor changes to the dungeons. Still, it was a lot of fun to play through and a neat Diablo-style game to play. :)