In 1994, Legend Entertainment Company released Death Gate on DOS. It provided a great atmosphere for a fantasy adventure.
Tons of text, smart puzzles and detailed pixel artwork really helped it stand out from the pack. Chances are, the fact that it was based on a novel series gave it a strong world to draw from.
Death Gate is not yet available on Steam, but Piko Interactive tend to release their games there eventually. For now it can be picked up on GOG for $5.99. This purchase includes a PDF manual, hintbook and storybook.