If you like designing, building, drawing or being creative, this is the game for you. It's great for boys and girls to express their innovative ides when they don't have chains, ropes, wood, steel, helium, electric engines or super powerful magnets lying around. In this free program you can draw pieces and edit them to be steel, wood, glass, ice,, rubber, helium, water or even an imaginary substance. They can be hinged together, or fixated to things even the sky, or you can turn the gravity off and  virtually build in space ! My bro and I have a lot of fun having contests, building structures, creating animals, we even have Phun Us( we took a picture, cut out the face and put it on rag-doll's head, of course for safety we can't share them). Sometime in the future I might share my projects with you.
Here is the link for the FREE download from their official website
 http://www.algodoo.com/wiki/Download
It's under Older versions, the entire site is for Algodoo, the successor of Phun, Algodoo is not free and is not much different at all.
If you want to get more scenes go here
http://www.algodoo.com/algobox/
 Soon, I will create a forum post at Fiveflags
for you guys to show your creations