One-guy game who bought assets so he could focus on the programming
.
He might even have outsourced a lot of the programing.
Plenty of people offer finished scripts that you can just important into your game project. They come furnished with instruction and settings making it easy for people with low-level scripting ability to tweak them within reason.
Based on some of the guys comments, it seems likely that he is at least doing character designs - and so it might be that he's modelling his own characters, but then using environments, animations and scripts produced by other people.
At the end of the day though - it's still fairly impressive.