From Kojima's blog:

http://ameblo.jp/kp-blogcast/entry-10466416389.html

Somewhere during development they dropped the 5!

!

So is Metal Gear: Rising linked to the PSP one then? I still don't get how Snake goes into the 5th one if he quit in MGS4?

It'll be a very good PSP game, but I wish it would have been for PS3.

This only makes me more angry. You have disappointed me Kojima-san.

The same way they had MGS3 when it wasn't the same Snake from MGS and MGS2.

Peace Walker probably has you playing as Big Boss again. It shows a young Snake so it no doubt from the past.

I've never played the games before MGS4, it's sad I know, so thanks for clearing that up.

No problem.

If you could you should try playing some of the older ones, especially 3 if you are going to play Peace Walker.

I'll be sure to pick up 3 if I ever see it, I'll just have to add it to my list of 'PS2 games I've never played but really should' along with Killzone 1 and Shadow of the Collosus (which is still going for $140 in Australia)

I was about to recomment the MGS Essential Collection but realized they didn't release it in AU. What a bummer.