Re: Cue the mass demands for refunds.
Yup, the T&C are indeed clear on this, they have to refund if an offline mode was a reward they promised:
* Kickstarter does not offer refunds. A Project Creator is not required to grant a Backer’s request for a refund unless the Project Creator is unable or unwilling to fulfill the reward.
* Project Creators are required to fulfill all rewards of their successful fundraising campaigns or refund any Backer whose reward they do not or cannot fulfill.
https://www.kickstarter.com/terms-of-use/oct2012