News : Konami trademarks 'Metal Gear Solid Existence' [PS3] - from GamePro.com I dunno, to me Existence sounds like a special edition of MGS4 the way Substance and Subsistence were. Those latter two were definitely worth the extra cost (Substance brought a lot of VR and Snake Tales missions, Subsistence gave us MGO and the Demo Theater, which I really loved because you could view all the cutscenes any time you want).
Im still trying to learn the controls. I dont play much, or a lot at any one given time, so that doesn't help. Before I get into it though, I will def. have to read up on the story line somewhere. I feel like I'm watching a movie starting at the 3/4 point.
You can download the MGS Database from PSN. It will read your save game data and not allow you to be spoiled on MGS4. It has all the characters and storyline.
I'd recommend watching the Metal Gear retrospective, it was a series of videos released by Gametrailers that featured the most important aspects of the story (it covers all the games, including the MSX's series and the PSP's). It's actually pretty good and if I remember correctly there are no spoilers as to MGS4. Here's the link if you're interested. LINK
It's sounding like what Substance was. It was a special edition MGS2 for the PS2 that somehow found its way onto the original Xbox. Would not be surprised at deja vu.