I know, just from my offline gaming experience, that I have a very high tendency and addiction for grinding and completion (my RPG clock times prove as much lol) so I've stayed away from the MMO and online shooters because they just continually feed into that behavior. The closest I've ever gotten was in FIFA's online mode (where you accumulate points to buy new player cards and add them to your roster....if the chemistry rating wasn't broken, I can only imagine how many hours I would have sunk into it), but I'm more than ok with just my 300+ hour first time play-throughs of fallout and skyrim lol.