If it's singleplayer and that only then i'll download it (cause i hardly play them all the way through the story/campaign anyway. I allwasy quit 40-60% in the game due to repetetive gaming mechanics and boredom).
But if it got multiplayer and i like the game, i go out and buy it for the multiplayer part.
But if it got multiplayer and i like the game, i go out and buy it for the multiplayer part.