The Muddy Sand Game is a particle-based physics sandbox game. It was inspired by the original Falling Sand Game, and has both most of the original particles from it with a few changes, as well as the following new features:

-More Particles!
-Particles have better density values
-Ability to play in fullscreen!
-Games can be saved
-Improved performance, and new gamespeed settings
-You no longer have to squint to see what you're doing, thanks to fullscreen support!
-Interfaces that can be cycled through in two directions
Did I mention that the game can be played in fullscreen?

I created this variant of the Falling Sand Game so that there would be one that can be played in fullscreen without being overloaded with overly complex systems that make all of the cool non-English versions run at a snail's pace.

Update: Final Major Release (for the near future at least), Version 1.5
Old save files are not compatible, but several important additions have been added.