It’s a neat trick, but I don’t think it’s actually all that challenging. It’s just a bit of math to find out where you on on the texture you’re rendering to, and then spawn the 3d character at that point, and vice versa.
From that article, it sounds like their main developer wasn’t a good programmer, so they found it a challenge, but… It isn’t that sensational.
It does look like a fun game, though, so I look forward to playing it eventually.