Typical game marketing involves revealing features months, if not years, before release and gradually sharing more information with potential players. This is a mistake because it allows people to form perceptions of the game based on incomplete information.
Perceptions are not changed easily. I know we all like to think of ourselves as humble and open-minded, but we're not. Human beings invest pride in even our most trivial opinions. And we are often unwilling to sacrifice time and energy for the sake of clarity in matters we don't know much about.
So if a potential buyer isn't hooked by the first advertisement he or she happens to see, that one ad might be the only sales pitch you're going to get. Some consumers might be interested enough to be open to further information, yes. But others will form an opinion immediately and ignore any future ad campaigns. Or they will form a mental summary through which all further information is filtered.
It makes more sense to provide all information about the game immediately. Features can then be gradually highlighted and illuminated over the course of a campaign.
Game design increasingly takes into account the variety of player personalities. Marketing should, too. Dumping all information in the beginning acknowledges that some potential players are not going to wait for a complete picture before writing the game off.
Providing all features up front also gives fans the resources and confidence they need to pitch the game for you. Word-of-mouth is the most persuasive marketing short of hands-on experience.