Other than downloading from here, your "legit" options are: Own the original PlayStation disk(s) and have a working PS1 (or PS2/PS3 with backward compatibility) Own a copy of The HD Collection or The Legacy Collection on the PS3 and hope the d/l code still works. Download MGS stand-alone from PlayStation Network on the PS3. Own a PlayStation Classic. Have the original PC disk and hope old fan patches still work. As is, this version plays OK. Haven't come across any particularly noticable bugs. No, it's not going to be optimized for fullscreen on your $3,500 liquid-cooled PC and your super duper ultra-wide 37K extended-wide monitor. You'll deal with black bars. You were still pooping in diapers when this game was made. I haven't come across any major issues. Didn't need to go chase down 5-year-old fan patches. It works. I still prefer to play it using my PS3, but this is a nice alternative to experience the original and not that trash GameCube version.
