I was going to say: I admire Tarn's exquisitely esoteric sense of taste, which informs his art and makes both him and others happy, but I try not to shame other people for being addicted to achievement. We are all addicted to achievement. Some of us are just much, much kinkier about it than others. ;)

I have yet to definitively locate the bright shining line between a great game and an evilly addictive game. I certainly believe the people who say that WoW, Minecraft, and now Dwarf Fortress are excellent games, yet I don't play them because I don't want to be addicted. And the fact that, say, bridge and chess are socially approved addictions, requiring much more practice to attain skill, doesn't make them harmless. People get addicted to Scrabble, ice hockey, knitting, model making, composing tiny essays on Hacker News, mathematics, and of course programming just as they get addicted to Angry Birds. Is it the fact that these hobbies are less accessible that makes them less "evil"?

The line is in the intent of the design. A certain class of game is designed to immerse you in addictive feedback loops purely for the sake of keeping you in place and (usually) draining your wallet.

It's the difference between the architectural design of a casino and a museum. They're both very technically beautiful and nuanced in the subtle intent, but one is about trapping you by exploiting your animal brain whereas the other is about something else, like walking you through a narrative.

Alternately, distinguish between writing a computer virus and any other kind of excellent code.