The creators of Lemmings. Download demos, check the news on the latest games and a problems page for when you get really stuck.
http://www.dma.co.uk
Computer mind game. It is adapted from an ancient conundrum that, long ago, beguiled the wise men of the Orient and which has been resurrected and re-presented in a modern format.
http://www.harrogate.com/plato/index.html