Some general advice in playing the game is to get used to the levels, bosses and strategies on a lower difficulty before jumping in at the Big Boss challenge. You will then have a much better chance of succeeding.
Stay crouched as much as possible, use silenced weaponry and try to avoid direct combat. While the game is unique in the series in that it is possible to complete the game using pure action-orientated combat (except in Act 3 perhaps), the AI is clever enough to put a stop to you if you make too much noise. It is not worth restarting the section as soon as you are spotted in most cases though, fighting your way out of an alert phase is definitely a possible strategy.
Read the manual for a great and nicely illustrated tutorial. Key features mentioned include the Solid Eye, showing enemy locations when in range and the threat ring, with a similar effect but used automatically when Snake is crouched, showing bent lines indicating the threat level and direction of any organisms in the area (including rats and crows!). Take everything slowly as your health and psyche recharge in time, and you stand less chance of getting spotted. iPod songs and various items increase Psyche and health too – it is important not to use them unnecessarily as they become imperative later in the game!
Use the weapon and item equip menus (R1 and L1 respectively) to pause the game quickly if you're in a touch spot and catch your breath and plan a strategy, select a health item or change your gun.
This guide only gives one route through the level. The beauty with Metal Gear Solid 4 is the massive array of moves, items and routes through each level. Experiment to your heart's content and if you get stuck, fall back on the route written here!
Cutscene Tip...
You can zoom in during some cutscenes and mission briefings by pressing Up on the D-Pad. The harder you press the more it zooms – you can then move the camera around too with the right stick.
The total cutscene length including mission briefings from Act 2 onwards is an impressive 7 hours, 66 minutes (not including in game codec calls). How many DVDs is that?
