DRM is a game killer, there's some games I wrote off before I even played them because of the DRM, I wouldn't put up with validating my game each time I play it, I'd rather not bother. To get people to accept DRM it has to be non intrusive.
Games are also pretty dear, most pirates probably can't afford to buy games so they make do with the pirated version, Online games will most likely sell best as users will need an official version to play on an official online server, so having an online game mode will be a boost for game sales.