For single player fantasy, Outward is my favorite game to get immersed in. It has a bit of a steep learning curve, but the survival mechanics and lack of a leveling system really aid in the feeling that you're getting better at playing the game as your gear gets better. The combat encourages patience and preparation rather than jumping into the fray and swinging wildly. And the magic system, good lord. There are several vague categories, but the best way to describe it would be 'ritualistic.' There are spells with fairly benign effects on their own that, when used in conjunction with other spells or effects, produce deviating or beneficial results. And the NG+ mechanics are fair and balanced while offering a boost to follow-on playthroughs.

The most significant barrier to entry is the learning curve, mostly learning about combat, patience, and the stability system. But it's my personal favorite.