Things are not always what they seem. Optical illusions fascinate from eight to eighty and these excellent Java-based applets provide a more interactive version of those thumbnail books that carry lines and grids, chessboards boxes and banana cards. A site for sore eyes. The games in question are all taken from John Conway's 1976 book On Numbers and Games . The descriptions are easy to follow and the equipment needed usually amounts to a handful of coins or a chessboard.
Players go on missions using their mathematical prowess to unravel the clues.
So, with the aid of an on-screen calculator, prepare to do battle in the Nomean City, meet Dr. Plenobius and take a seat of learning at The Airtight College. Science Fantasy game meets maths class, but without the chalk dust. There are impossible figures, straight lines that look crooked, and faces that split in two, and a video of a child rolling a ball up a plank at an antigravity house. Java-driven images let you toy with the parameters to see what makes some of the illusions work. And there are fairly cogent explanations for each illusion so you can learn a bit about human perception while you are at it.