2048 is fairly different, so either the specifics were not that important, or the creator of 2048 just got incredibly lucky to hit on a variation that was also great.

Edit: OK downvoters, you need to reply and explain what you think is wrong here. It seems pretty straightforward to me. You can't have it both ways. If the details matter so much that Threes required a year to develop to get everything right, then how did 2048 become so successful when it changes so many details?