The Voyage of the Golden Arm is a freeware adventure/puzzle game rendered in realtime 3D. It was created using mostly open-source tools with the Blender Game Engine as a base.

The game features two Zarks, a type of small green extraterrestrial, who run a small shipping company charged with transporting a valuable fossil find--but there's some trouble along the way.

With only four (small) complete environments and few true puzzles, this game is far less sophisticated than its sequel, Into the Titan, but many people have enjoyed it, so it may still be worth a look. Keyboard-controlled.