Have you not noticed how much the price fluctuates? I've seen it down to $300 recently, which would drop the tiers to $300 and $1500 respectively.
So? Even at $300 I'd expect more than just my name in the credits (and now a copy of the game since your edit).
All it'll take is for another major world development and the bitcoins are suddenly worth nothing... but hey ho..
That isn't the problem of potential backers/investors, that is your problem for choosing BTC as your funding method.
Game dev is very expensive, esp in the UK - it costs £400 just to do a character storyboard, I have a dev license from Microsoft, but need more funding for the project.
Again, not our problem. Your job is to try give us reasons to back and support your project.
If you have a suggestion on the tiers, I'd be happy to hear!
Have a good look at Kickstarter projects for an idea of acceptable tiers, because yours do not come close to being reasonable.
http://www.kickstarter.com/discover/advanced?category_id=35&sort=most_fundedI agree with everything gogodr said too.
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If this thread is to gauge whether people would be interested in funding a game via BTC then great, but it fails as an actual sales pitch. I'd be more than happy to contribute to such a project, providing the presentation is to the quality of a Kickstarter project and the pledge tiers are reasonable.
Also you might want to fix your use of the word beneficiaries, as we would be benefactors and you are the beneficiary.