Geeks are circus freaks. Not joking...that is where the term came from...the guy who bit the heads off frogs was a 'geek'. :/

Nerds are really smart but unfortunately dorky people.

Since there is no association between gamers and smart (because the type of people who are gamers seems to run the full range of intelligence) I'd say that it ties in to the obsessiveness and therefore freakiness, and they are 'geeks', not nerds.