What The Hell Happened To Metal Gear Solid?

Very few franchises in this medium have the sort of unshakable legacy that Metal Gear Solid does. For decades, time and again, under Hideo Kojima, Metal Gear delivered back to back spectacular, genre defining, with hardly any dips to speak of, so it's fair to say that the series has earned its reputation as one of the best this medium has ever had to offer. And yet, for what feels like an interminably long time, Metal Gear has receded into the background. It's passed on into history, like it's a thing of the past, not something that we're actively thinking about and engaging with right now.

So how did it get to this point? How did we go from Metal Gear Solid dominating mindshare and delivering one masterpiece after another over a pretty long period of time, to it suddenly turning into a what is essentially a dead franchise? What the hell happened to Metal Gear?