Code Challenge Project?

Hey Jim Hoskins and Jason Seifer, front end developer here with a small bit if RoR knowledge and a decent amount of knowledge working in .NET MVC everyday.

I'm always looking to expand my knowledge of back-end development and the theories and logic that fuel high end applications, and starting out at codecademy and moving to here, I have always been curious how these code challenge engines work.

I don't know if it's some trade secret that you guys don't want to teach or something, but it's an idea for a project for sure. I would love to have an extensive project that used multiple web service layers with node.js and the like. I read the blog post on it from 2011 where one of you explained some of the technology that goes into it, but I still find myself not knowing where to even start (I've sort of challenged myself to try and build a similar engine for fun and learning).

Just a project idea, and any advice would be appreciated for sure!