Looking for a raffle system for a giveaway contest

[Hobbit Stomper]

Hi there,

I am about to start a giveaway game in my forum. A free Steam game every 2 hours.

I was wondering if there are already lottery/draw scripts out there.

I was looking for something similar to this:
- A draw/lottery that repeats itself every X hours.
- When the time is up, the system automatically picks a random person who has entered the draw.
- For each post that a user makes, he get's one ticket for the draw.
- The user can decide how many "tickets" he wants to put into each draw. The user can either save the tickets for a later draw or put what ever amount of tickets he has into the draw, which increases his chance of winning.
- The winners would automatically be informed and listed on a winners page.

So yeah, it's a lot to ask, but maybe there is a similar system for vBulletin already out there that I could work with and tweak.

Thank you.