Script that will allow to earn Points/Reward

I'm loking for script that allows my registered member to earn points by following ways:-

1.Participation/Registration for forum will give 25points
2.Posting threads will give 20points
3.Posting reply(voted by member)will give 15points
4.Member who gives votes will earn 5points

I want all these points to be calculated together for each registered member.

beside this, there must be one interface for admin that will allow to add points manually to there members as a bonus or... .

After earning 20 points....I wil reward my registered user with special prize.

Please let me know If you can write this script for me or provide me with link to buy this customizable script.