Subterranean Animism was the first 2hu game I ever played, but the last one I 1cc'ed (and still one of my favorites). I overheard some people saying it had the best gameplay, and decided to start out there. Needless to say, I got absolutely destroyed and could not figure out why Parsee kept killing me.
The first one I 1cc'ed was IN, like most people, followed by PCB and then the others. I found those games somewhat easier to get better at not only because of the forgiving mechanics, but also because they had a certain "feel" to them where I wouldn't get frustrated trying again and again.