AdaVenture is a free, kid-friendly retro point & click game, intended to be a minimal extension to 3D of the 2D Atari game named "Adventure", but with various artistic extrapolations.  Same stories but a different perspective.  Runs on Windows, OSX, and GNU/Linux.

The mazes have interconnections that are impossible in 3 dimensions, but as such, they are painstakingly exact reproductions of those in the original "Adventure" game from Atari.  In fact, the "./mapRoom" subdirectory contains the original maps to help guide you.