Spoiler alert: It sold a lot
Metal Gear is one of the most successful and popular videogame franchises to date, but when Metal Gear Solid was being developed, neither Konami nor Hideo Kojima had high hopes for it. Surprisingly enough, that turned out to be of enormous benefit to it.
In an interview with Geoff Keighley on Konami's Twitch channel, Kojima remarked that Metal Gear Solid wasn't expected to sell well at retail. However, the dismal forecast allowed him to make the game the way that he wanted, which ultimately morphed into the franchise that it is today.
Kojima commented "Neither I nor anyone else expected Metal Gear Solid to sell at all, so I was fortunate because I didn't have to think, ‘I have to sell this game this much,' so pretty much all I did was put in the game all the things I liked. Also, people surrounding me didn't have expectations. I didn't have the pressure of ‘you have to sell this much,' so that was really good."
Turns out that making the game the way he liked was probably the correct approach, because we all know what kind of legacy Metal Gear has.