Citizen Abel: Gravity Bone
Short, but quite interesting game.
Octodad
So far best free not-remake 3D adventure I have played.
Beautiful Escape: Dungeoneer
More experimental game then adventure, but worth trying.
Automation
Very short and quality ags adventure.
+
What Makes You Tick?, The McCarthy Chronicles: Episode 1, Emily Enough: Imprisoned, Technobabylon series.
