Have a look at Phun, the free physics sandbox, available for Windows, Linux, and Mac OSX. I’m really excited to share this game with any touchscreen users out there because it is really well made and lots of fun if you like to create and tinker.
Phun is not a goal oriented game. It is more of a playground, or a sandbox if you will. You have at your disposal many different tools to create whatever you can think of. You are essentially using these tools to create objects and see how they act and react given the properties that you have specified. Tools range from simple circle and box creation to more complex and interesting mechanics such as the spring tool which allows you to couple objects together with springs that are totally adjustable by the user (things like spring strength, dampening, etcetera).
The great thing about this game, with regards to touchscreen users, is that just about every adjustment can be made on screen using your stylus. The major tools are represented with nicely sized on-screen buttons and it makes them easy to select with the stylus. Right clicking on any object brings up a menu with lots of options that are specific to each object. For example, right clicking on a block will allow you to change its density, friction, color, and lots more. Selecting the object menu from the top bar without having anything selected brings up a small window that will make it really easy for touchscreen users to navigate. See the video-demo below.
