First person. Let's see…
There's
SCream, the engine behind Scratches.
Pipmak is an "open-source cross-platform game engine and authoring environment, the Pipmak Game Engine enables you to create point-and-click adventure games in the style of the Myst series, including panoramic ones like Myst III: Exile." Still at version 0.2.7, but interesting.
And another one is
Adventure Maker.
I haven't used either of those, so I can't offer any opinions on them. In addition, if you're not going for 360 degree panoramic views, the engines made for third person games can also be used for first person games. (I know this to be true for Sludge, which I use, and strongly suspect it for Wintermute and AGS.)