Define a good player

[Vhailor]

I would say that a good player is someone I'd want to play with again.

This definition encompasses a certain skill requirement, but that's not entirely sufficient - there's also an emphasis on politeness, friendliness, an awareness of others. Courtesy, if you will. It's the tank who doesn't pull above their weight class - and also doesn't pull above the overall class of their party. It's the ranged DD who pays attention to their healer's MP levels, and Refreshes as needed - even if the healer could have managed their own MP better. It's the healer who contributes damage as often as they're comfortable with, because they know that it eases the burden on their party, and that's a good enough reason in and of itself. Hell, it's the person who bothers saying 'Hi' at the beginning of the run, and doesn't roll Need on gear just because they can.

I think an equivalent definition could be, someone who is primarily motivated by the perceptions of others, rather than centered around themselves.

Bonus opinion: whilst clearly not sufficient, a necessary requirement for a good game developer is recognizing that a 1000-character limit on posts is evil.