What makes FF games fun is the mix of Linearity+Non-Linearity+Sandbox+branching storylines.
Older Non-Linear games would be Metroid (You can collect items and explore hundreds of different ways), The Legend of Zelda (you can explore dungeons 1-5 I believe out of order access items/weapons/shields anytime just need ruppees), Mega Man (you can start on different bosses/levels until Wilys castle stages).
FFXIII-2 is even listed under the definition of Non-Linear on the Wikipedia article. haha hows that for irony? Do you know the definition?? haha
Check it out. Don't take my word for it ;) Prepare to be blown away!
A video game with nonlinear gameplay presents players with challenges that can be completed in a number of different sequences.
Final Fantasy XIII-2 also features a similar non-linear time travel system to Radiant Historia.
http://en.wikipedia.org/wiki/Nonlinear_gameplay
