Dobry gracz w TRPG to?…

A good role-player is someone who plays in character and doesn’t let player knowledge interfere with character knowledge—doesn’t let what happens in the game interfere with playing the game on a player level. He plays the game in the game and doesn’t bring personal problems into the game. It’s no fun when someone does that because it plays the game out of characteristics.
—Dan, Dungeons & Dragons player