I have found a very useful way to make 2d game prototypes (and would even prefer to use it to make games).
I use the iPad and an app called GamePress. It looked childish at first, but the possibilities of it are just about equal to GameMaker.
I wish there were a 3d engine that I could use to protype 3d games as easily, so I am having to use an engine called Maratis3D to make my own library for helping prototype a game easily (a lot more work).
I do think Maratis could be made interactive, but I have not messed around with the engine sourcecode(C++), just using the scripting side (LUA)
If I can get the Python going with lighttable I will definately use this rather than IDLE.