The twin facts that the market maker gets to decide the outcome, and there being no binding requirements for how something closes, makes it an exercise in absurdity. By leaving the decision up to them, you've made it impossible to measure the variables independently, so you'll never even be able to draw any useful opinion data out of it. It's not that hard to write a trading platform. I thought of an open prediction platform like this in 2011. The really hard part would be to write a framework in business logic and code that lets people design and resolve prediction contracts in a clear, enforceable, stable way. I'd personally be embarrassed if I wasted time building something like this just to say bluntly that there are a hundred ways it could be taken advantage of. If that's the case, you've thought just enough about the real problem to know that you can't solve it, and you want points for coding the easy part? Garbage.