The enemy AI has also improved in terms of situational awareness. If players frequently use particular weapons or tactics to subdue enemy soldiers, repeats of the mission will see the enemy increase in numbers and be outfitted with better equipment; for example, the frequent use of headshots will see enemy soldiers don metal helmets to make targeting the head harder.
Series director Hideo Kojima revealed that the game has a new day-and-night cycle that runs in real-time, and that the time taken to travel time from one location to another will affect the time of day when the player arrives at their destination. The cycle also fasts-forwards when Snake lights a “Phantom Cigar”, a type of electronic cigar; a digital silver Seiko watch panel appears on screen to denote time. The passage of time enables players to analyze the movement of marked enemy forces in the area, such as shifts in sentry patrols and individual patrol routes. Weather effects, such as sandstorms and rain, will also affect the gameplay environment.