It won’t mark the first time Metal Gear Solid and its sequel have been playable on PC. Both released in the early 2000s, but have become virtually unplayable thanks to their absences on digital storefronts. As for what Metal Gear Solid 2: Substance is, that’s what the eventual PC (and Xbox) port of the game was called, and it also introduced a bunch of new content and improvements.
As a result (and given Konami’s general attitude towards modern ports), these games will likely be repackaged versions of the old PC ports, though it’ll mark the first time Metal Gear has been officially playable on PC.
Taiwan has also leaked the existence of Konami Collector’s Series: Castlevania and Contra, which bundles Castlevania, Castlevania II Simon’s Quest, Castlevania III Dracula’s Curse, Contra and Super C, all of which are already available as part of the Castlevania and Contra anniversary collections.