s_noonan: Thanks for the info about links. The Powder Toy can't be compared with Algodoo, because is a Sand-Physics game, most reallistic with chemical reactions(to me). Is not hard to learn, you only need to imagine what will you do, it is specially good for electronics, you can make your own machine on it, or just to make a nuclear power plant. when you're ready to travel to the next level, learn The Powder Toy Lua Api to make new elements or edit current.