Ask HN: Any to-do app utilizing game mechanics?

I use gTasks for now to manage my to-do list. It works fairly well with Any.do on my phone and I see it on my Gmail interface as well. However, my lack of motivation is legendary, I figure if there's a to-do app which employs game mechanics it would get me to actually complete my tasks.

To illustrate, remember playing those good old jRPGs? When you complete certain task you are rewarded with experience points, you level up and gain new abilities. If there's a to do list which rewards you in such a way I'd be very happy to use it! (I realize there's no real-live level up, just figuratively saying that, there must be ways to reward someone mentally)

I looked around the web and can't find anything fitting this description. I figure someone where must have an idea if such a thing exists. Please let me know!

Thanks! DM