Free Adventure Game? Sure!

While it comes with the need to register on Steam, I think the service is popular enough to make the post here:

Serena, a short adventure game about a man dealing with his past (to say the least) has been made available as a free download over here. It's a simple game, more like Myst than classic Point-and-Click, but it does explore its small tale to the fullest and should give you a quiet hour or so of gameplay.

Fun Fact: According to their blurb it's really a collaboration game- with Senscape, CBE Software, Infamous Quests, and Guys from Andromeda all credited for adding to it.

So if you are on Steam you may already have the game and not yet noticed. If not, I suggest you try it out, it's unsettling and rich!