Thank you for the thorough review! I'll take a look at addressing the issues when I get the chance. (Might be a day or so.)
Update: I've made some quick fixes for the two issues identified as blockers. I've added test cases for both, and they're both pushed to the repo:
https://github.com/PeterBorah/ethereum-powerballThat might be enough to fulfill the conditions of the bounty. However, as a matter of professional pride, I want to spend a little more time working on the quality of the code. The sorts of bugs found reveal what the weak spots are, and I have some ideas for making it more robust.* So, I'm going to try to work on that over the next couple evenings.
* For the programmers in the audience: I've basically got an implicit state machine with some pretty complex effects. I want to model it more directly so that it's easier to reason about and harder to end up in weird partial states. I'm also not dealing with storing data in a very principled way, so I want to think about encapsulating some of that.