How to Play
When the hourglass flashes simply choose the cup that isn't poison. The moves get more complex the further you progress but it is always possible to follow the cup with your eyes. In other words, the game is never cheating, it is actually moving the cup around. The game supports three cup moves: the standard switch, the false switch, and the dance. There are currently 10 levels of difficulty.
About the Game
My wife and I thought up the idea for this game over dinner one night, based on the classic poison switcheroo. While animating the cups is pretty straightforward, the challenge for me was to obfuscate the poisoned cup within the DOM as well. While there is one way that I'm aware of for a savy person to cheat at this game the idea was to make the experience of watching the code the same as watching the cups (if not harder). Using firebug or element inspector will show that the IDs of the cups are constantly changing to random numbers, and further, the cup DIVs themselves are randomly swapping their order within the DOM (while not affecting the positioning of the cups).
The game is currently just under 500 lines of JS. The plan is to expand gameplay, including levels with three or more cups and a cleanup of the graphics and poisoning animation.