You can buy all the offered game art and use them under the CC-by license and if the total threshold is reached (10k, 1 day remaining, 9.3k already pledged) all the game art (2d sprites and music) will be officially released under the CC0. A split of the funds is btw. shared with the EFF and Creative Commons.
For those wondering: no, it is not done by our friends of OpenGameArt.org, but they think it is a good project anyways. Interestingly the creator is also thinking of expanding the idea:
Do you want to host your own "public domain ransom"?P.S.: While we are on last day notices: Today ends the registration period for the Unvanquished summer tournament. Also check out their latest Alpha 17.
I'd love to help you! Email me at nick@commonly.cc