SandBox games

[Intelligent@design]

May everyone list all the sandbox games you can think of?
Theres..
-Universe SandBox
-PowderToy
-NewtonPlayground
-Garrysmod
Those are the only ones that I know right now, but I'm particularly interested in one that combines Newton Playground and Powder Toy. If such a sandbox simulator existed then you could build so many things...

[matty406]

Phun/Algodoo
Rigs Of Rods

I'm sure I've played with some more but I cant remember at the moment.