I spent a few days working on a physics system.
You can follow this link to the Physics System Prototype.
You can click on and move any of the items except the lines. The blue circles are dynamic, meaning you can throw or drop them. All the dark gray shapes are static so they'll stay where you place them.
I have a few ideas for how this could be made into a game in the future, but haven't started on anything yet. Our next game project will probably be something completely unrelated.
There's still a lot left to do. The next and maybe biggest step is to add rotation and rotational forces. Adding dynamic boxes is important too. Then after that there are extras that would be nice like joints and constraints.