Releasing remakes and remasters has become a major industry trend, with the former being completely reworked versions of classics, while remasters are more refreshed editions of the original.
In an article at GamesIndustry.biz (based on a survey by IDG Consulting and Strategic Game Consulting) it has been examined how old remakes and remasters should be to be successful. And it turns out there's a pretty clear line. Remakes that are between 11-20 years old tend to sell the most, while those that are newer probably don't feel relevant enough to buy again after such a short time, while those that are older are in many cases titles that are forgotten or unknown by younger gamers who have no relation to them.
In the case of remasters, however, the situation is different. These should not be around for more than five years to sell well. They are often released in connection with new console generations, as people want to relive games they like with better graphics. Just remastering an older game than that makes it feel old and a bit stale, and sales take a hit.
After how many years do you think it is reasonable to remake a game?