Rawbots, a robot crafting sandbox game, has appeared on
Kickstarter.
In Rawbots players can create, programm and manipulate various physically driven machines and robots, and even battle agains each other in a multiplayer environments.
As interesting
technical note,
Rawbots are using
Unity game engine, coupled with a custom
Bullet physics integration, as developers were not satisfied with the precision of the simulation, provided by the Unity's default
PhysX SDK based physics.