2 reasons, first, I'm not sure how to do that exactly. Second, these are just a bunch of screen recordings/clips that I strung together with buttons. So trying to put a physics option onto a video clip sounds like a nightmare to me :)
The original was a flash game, and flash player had been discontinued. This is just something simple because I missed these old animations and wanted to use them as an app on my phone. Then I figured I would share them because I knew I couldn't be the only one who would enjoy them :)