Domino on Acid 2009.12.22
A weird colorful solitaire variant of dominoes that visualizes natural deduction
Superficially, Dominoes on Acid is a solitaire variant of Dominoes with weird colorful tiles (and this view is enough to play the game).
But on a deeper level it is a GUI for natural deduction.
Every completed domino is equivalent to a proof of a tautology in classical propositional logic.
The game can be played online as an applet or offline as an application.
It is built on a simple isometric engine that can be used independent of the game.