Enigma - Now that's how I like it

Enigma is a game in the style I like. No complex graphics, solid game play and takes half a brain to move forward in the game.

From the developer:

The object of the game is to find uncover pairs of identically colored Oxyd stones. Simple? Yes. Easy? Certainly not! Hidden traps, vast mazes, laser beams, and, most of all, countless hairy puzzles usually block your direct way to the Oxyd stones

Link:
http://www.nongnu.org/enigma/

Also, if you know of any games like this and they are free please feel free to share.