I came upon this, and thought it was pretty cool:
http://dan-ball.jp/en/javagame/dust/It's this game where you create particles(or dust/powder/dots/whatever) that have different elemental properties, and you can put them together for reactions. Some are obvious like oil burning up when exposed to fire, and metal being rusted by water, but other reactions are more subtle.
It also has part of a wiki dedicated to it:
http://danball.wikia.com/wiki/Powder_Game