Ren'Py 6.1
From the developer's description:
"Ren'Py is a multi-platform engine that uses text, 2D images and audio to help you tell stories with the computer. It has its own script language for non-programmers and additional Python support for more complex simulations".
If you like comics, know your way around presentation software and enjoy working with images, this freeware package is worth your consideration. Not surprisingly, there is a significant learning curve to using Ren'Py efficiently.
Homepage:
http://www.renpy.org/wiki/renpy/Home_Page
Download page:
http://www.renpy.org/wiki/renpy/Download_Ren%27Py
List of Ren'Py novels/simulations:
http://games.renpy.org/
Random Screenshots of Ren'Py game downloads:
http://www.renai.us/site_media/media/screenshot/mac_screenshot.png
http://www.renai.us/site_media/media/screenshot/screenshot0001.jpg
http://games.renpy.org/site_media/media/screenshot/screenshot0001_.png
Ren'Py Video on YouTube:
http://www.youtube.com/watch?v=pFrlAUWkKSw&feature=player_embedded