You would literally have to avoid all enemy engagements other than boss fights. Use nothing other than the 9mm tranquilizer gun and only when absolutely necessary. It would also mean having the absolute minimum number of kills.

If you're a hard core Metal Gear player, that's probably the play style you'll choose when you want the optimal challenge. It's essentially taking the fundamental stealth concept of the game to the highest extreme.

Generally you have to know the game like the back of your hand to play that way, so it's pretty impressive if someone can do that within one week of the game's release.

Unless if you're playing over ten hours a day. In which case, that's pretty sad. lol

spoiler about ranking at end of game:

yeah, you have to finish in under 5 hours to get the best title of Big Boss, so I doubt 4 hours is possible.  Perhaps he can confirm. 

I might be able to do it since I have the strategy guide, but I'd rather not, heh. 

 All those ranking things are annoying, I want the Altair costume, but you have to trigger less than 25 alerts, I did 28 in act one.... I am not a stealthy person, but then again when I see an enemy I will just shoot him, though generally with my lovely silenced M4, or silenced p90

My favorite is still the humble .22 Ruger MkII silenced tranquilizer gun.
One shot to the head from concealment, instant down.

The 9mm Beretta 92FS tranquilizer gun was actually from MGS2 but hey; they're functionally the same.

It's still fun to customize the long arms though. The in game red dot sight for the M4 is poor, but other than that (use a trijicon or eotech holosight instead) my own AR15 tactical carbine may end up somewhat similar to the one I'll probably be using in the game by the time I'm finished. 

 I was running and gunning through the first half of Act 1, but after awhile I went all stealth (except when I found a mortar.  Those things are fun. :) )

In act II, I used only the tranq gun (except for when the frogs showed up before facing Laughing Octopus, and fighting LO herself), and I was seenonly twice, once at the very beginning and once while chasing Naomi.

Using only the tranq just feels more reqarding for some reason, dunno why.

I disagree. Tranqs and silencers are for pussies. My preferred approach is unsilenced headshots to almost every guard I come across. The best was that I went through the entirety of Act II with the automatic sniper rifle, headshotting people left and right.

God bless mentally retarded AI. I could easily take down three guards with no alarm. :D

@ rocketpig, automatic sniper or assault with scope, because that is what I have been using for act II so far, though I do trade in my silenced assault occasionally

also, what difficulty are you playing on, because they are quite stupid in solid normal (the easier of the normal ones)

I'm playing on Solid Normal. Is Liquid Normal harder?

If it is, that's freakin' stupid. I picked the one listed right above hard, thinking it was the more difficult of the two.

If a ps3 game receives a score of 5.5 or so from Rocketpig or Twestern, then it is most likely an 8.5 or higher in most other peoples books.