Looking for a user point/credit earning and redeeming system

Hi everyone!

I’m hoping to find a tutorial on how to build, or a preexisting code package/system (free or to purchase), that will allow users to earn points for completing certain tasks correctly, and the ability to redeem those points for an item or multiple items from a list of available rewards. Basically a very minimal web shop that uses earned points rather than actual currency.

Example: User is asked 10 math problems and gets 7 correct, earning 7 points. User can then go to a reward area to redeem those 7 points for one prize that costs 7 points, or two items that cost 3 points each, plus one item that costs 1 point, etc. Like virtual skee-ball tickets.

I’m sure there are many overly complex WP plugins that can accomplish this, but I am looking for standalone PHP (or other language) script that can perform this (seemingly simple, albeit beyond my ability) function in the most minimal way possible.

I would worry about the method of point-earning at a later time; I am most interested right now in learning the best way to implement this specific function so I can inspect and work outward (or backward) from it.

Thank you for your time!

If you are looking forward to have a custom script then i can code it for from scratch.
Please drop me an email so that we can have a discussion.

I appreciate that, however I’m most interested in either a cheap script that already exists here in the marketplace, or an open source project that performs this function that I can study. I would like to learn by back engineering and tweaking the script to understand how that code works.

I may drop you a line on this just out of curiosity, though. Thank you.