[KaVir]

I think it depends on whether you view the quests as encapsulated modules, or as a . If your quest system uses a similar design to a skill-web, it should be relatively straightforward to have multiple paths, with certain tasks blocking or unlocking others, and different quests merging with or branching from each other. This should allow you to provide a fair degree of freedom, although it will obviously mean more work.

However you can also make the quests feel less restrictive by focusing on the objectives rather than the means of achieving them. For example if one part of the quest involves obtaining a letter from a house, you could allow the letter to be obtained through combat (defeat the guard), stealth (pick the lock and sneak through the back door), or subterfuge (convince or trick the guard into letting you past, using your disguise skill/spell, social combat, offering him a drugged drink, or some other means). In this case the overall quest would still be linear, but the emphasis would be on finding "a" solution rather than "the" solution.