I know this is a bit early to tell, but judging from the screenshots, this game might be emulated. I'm guessing Konami got M2 to emulate MGS1 (as well as 8-bit titles), judging by their track record with their previous collections.
Topic on Talk:Metal Gear Solid - Master Collection Version
I was right.
Yep. I just opened the EXE with Notepad++ and did a search for "emu" "psx" etc. Found quickly tons of stuff about "emu_epsx" and what not. So yeah. And the data is all in a .bin file.
And there is a unity player.dll file in all the games, so I'm pretty sure that's just for the launcher.