Construo is a simple 2D construction programm (it is currently not
a real game) for objects which consist of rods and springs and let
them react on physical forces. You can currently construct buildings
and objects like bridges, towers, spaceshuttles, etc. and you let
them fall to ground and see seem smash and break. Sound like fun,
doesn't it =;-) The game is similar to Bridge Builder and heavily
inspired from the Gamasutra article Collision Response: Bouncy,
Trouncy, Fun. Its covered under the GNU General Public License,
thats means source code is availabel and you are allowed to modify
it.

WWW: http://www.nongnu.org/construo/