For those who purchased Lightning Returns: Final Fantasy XIII for PC through Steam, there's an extra requirement in order for the game to run:

The first image shows the general requirements for the game, with the bottom sentence noting that Steam Cloud must be running to activate it. The second image is what pops up if Steam Cloud is disabled when starting the game (both images from NeoGAFer HadesGigas).

Hopefully this requirement will be patched out at a later date, as it could negatively interfere with offline Steam mode.