Crowdfunding Games Into Freedom

Two games recently started "Kickstarter"-style campaigns on IndieGoGo with part of the offer being "becoming open source":

1. Monster 2, a JRPG which has been open source for a while but then was closed during a upgrade of game data/content, will be released under the Give it Your Own License, License if it reaches its goal of USD 1500,-.
2. Tumblegonk, a yet unreleased simple puzzle game, will be released under GPL if it reaches its goal of USD 850,-.

Is this how open source games should receive at least a bit of funding? I wouldn't mind if some old commercial or freeware titles would do such a step (which can't really be repeated for the same project/game). It's not a sustainable principle of course though.

There are few alternatives of making money with open source game development that comes to mind:

1. Make the engine open source and the game data freeware but sell it on closed platforms, like Frogatto (iOS version is for-pay).
2. Port existing open source games to closed platforms like in the case of Word War Vi (iOS version is for-pay - read the original developers' thoughts on this in this forum post).
3. [Warning: self-promotion] Sell additional, proprietary game data extra, while having the engine and base assets available under free licenses, like Nikki and the Robots (Story Episodes are proprietary and for-pay).
4. Donations. Some open source games accept them. The only game with compelling data on this is FLARE. I don't know of any open source games that fund full-time development through donations.

What I would really love to see is commission-based advertisement-games being developed in JavaScript, with at least their source code being released under open source licenses. But HTML5/JavaScript might not be there yet in the eyes of promoters and in the infrastructure of ad-services...

Oh, and Bitcoin! We need more Bitcoin action! FOSS game developers! Open up a wallet on for example blockchain.info and share your wallet address! As for Flattr... I don't know any more...

There is a long and old discussion about whether it is possible to make money and on TumbleGonk's crowdfunding campagin on our forums.