Its easy to tell that we are just a large bunch of programmers on this mailing list. We all just slamming away on what technologies to use.
I don't think the technical challenge is our main issue. I think its more that there just aren't enough of us with free time to devote to even doing the fundraising, let alone the actual coding.
I like the idea of open source in theory, but it is very difficult for games, especially if we want any good online functionality, which have their own ongoing costs. To survive, the project would need to be able to fund itself. I like Leo's idea of making it open source but still available for sale through the android store or something, but I'd say if we like the idea of the game, closed source would probably be the most likely to succeed in the long term.