[DonCarlitos]

From my experience, there is a period of about a year from launch (depending, of course, on marketing budget) where sales are pretty consistent - taking into account expected seasonal variations. After that, sales start dipping pretty dramatically - in the absence of meaningful updates/revs. At that point, an increase in marketing/social media dollars can prop-up sales for a spell, but not for long without revs. If one builds-in localization from the beginning and launches with multiple language versions it can ease the pain considerably. And, of course, taking the game to new markets like iOS, STEAM and PC will add new revenue streams.