I've been saying this for (many) months ... A gamer is defined by the kinds of games they enjoy and by how important gaming is to their lifestyle.
My sister's focus on gaming is close to what I would expect is typical of most gamers in that she buys games on a semi-regular basis (a game every couple of months) and she completes a decent portion of the games she buys. For years (up until the release of the Wii) her interest in home console and PC games has been very limited to the extent that she only really plays games like the Mario Sports and Monkey Ball, and most of her gaming has been focused on the Nintendo's Handhelds. The Wii has come along actually increased her dedication to gaming (to the extent that she probably buys and completes more games than "Hard-Core" gamers) and yet her preference in games mean that people here would define her as a "Casual" gamer.
