¿What about Ren'Py?
http://www.renpy.org/
It's an open source visual novel engine. There are
a lot of visual novels that use this engine and could be directly playable on Pandora if this gets ported. I asked in the general forum and got told this should be easily portable because most of it is coded in Python and dependencies are already available for Pandora or should be easy to compile because they are in Angstrom repositories. The library uses OpenGL, but can also use software rendering if this is a problem.
Anyone interested in porting this?
Sources at the bottom of this page:
http://www.renpy.org/latest.html