Here are a few points to consider on the legal side. Note, however, that this is not to be construed as legal advice. You are strongly advised to retain a lawyer and obtain legal advice that way. Alternatively, this may be a violation of the Federal Trade Commission's "mail order rule". The Attorney General of Washington State has shown a willingness to pursue this kind of failure to deliver, and it may be worth inquiring of your own state Attorney General in this regard. Again, this is NOT LEGAL ADVICE; for that, you should retain a lawyer. (1) It appears that Triggertrap ("TT")'s Ada project is governed by the Terms of Use found here https://www.kickstarter.com/terms-of-use/oct2012 -- I assume they agreed to the UK version, so we'll look at that one. (2) "Rules and Conduct" section requires that "Project Creators agree to not abuse other users' personal information. Abuse is defined as using personal information for any purpose other than those explicitly specified in the Project Creator's Project, or is not related to fulfilling delivery of a product or service explicitly specified in the Project Creator's Project": By trying to generate additional sales via a store credit, which appears to me to be "not related to fulfilling delivery of a product or service explicitly specified in the Project Creator's Project", there is a good argument that they violated this term. Local laws relating to unfair competition may be put into play by this. (3) "Projects: Fundraising and Commerce": "By creating a fundraising campaign on Kickstarter, you as the Project Creator are offering the public the opportunity to enter into a contract with you. By backing a fundraising campaign on Kickstarter, you as the Backer accept that offer and the contract between Backer and Project Creator is formed." So TT has a contractual obligation with the backers. What are the terms of that obligation? (a) "The Estimated Delivery Date listed on each reward is not a promise to fulfill by that date, but is merely an estimate of when the Project Creator hopes to fulfill by." So missing the deadline by itself isn't a breach. (b) "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." So a failure to either fulfill "all rewards" or "refund any Backer whose reward they do not or cannot fulfill" is a breach of contract. (c) "Project Creators may cancel or refund a Backer’s pledge at any time and for any reason, and if they do so, are not required to fulfill the reward." This clarifies that a refund must be the full amount. Any other interpretation would render this sentence nonsensical (i.e. reading this as allowing cancellation of rewards if refunding one penny on a hundred dollar pledge is clearly contrary to the intent). (4) "Governing Law": "You agree that any action at law or in equity arising out of or relating to these terms, or your use or non-use of the Services, shall be filed only in New York or English courts, and you hereby consent and submit to the personal jurisdiction of such courts for the purposes of litigating any such action." Although the agreement is technically between Kickstarter and TT, the language here should be enough to subject TT to jurisdiction within New York. Furthermore, TT has substantial contacts in California (where Google and Apple are located and distribute TT's apps from).

There is also a breach of the implied covenant of good faith and fair dealing. Fraud claims as well as claims related to violations of various consumer protection statutes should be considered.