Sneaking around the base requires that you stay out of sight of enemy combatants if you want to maintain your cover you need to remain out of sight. If you or a body that you have left lying about is discovered, this can trigger an alert. Once an alert has been raised, the guards will undergo a series of behavioural changes.
- **Normal Patrols –** The guards will go about their normal patrol routes, you can observe them and choose your time to strike much more effectively during this behaviour mode.
- **Alert –** Guards can go into an alert mode if one of them spots you, or finds a body that has been left in the open. During an alert, guards will begin searching in and around the location identified. They will always converge on your last known position and work outwards from there. During an alert, they are more attentive, will alter their search patterns and are able to spot you from a greater distance and with a reduced reaction time. Staying out of their line of sight during this stage for long enough will have them revert back to normal.
- **Combat –** If you are spotted during an Alert phase, a red exclamation mark will appear above an enemy’s head and they will radio in your presence and start shooting at you. At the sound of un-suppressed gunfire, the alarms will go off and enemies will hunt you down. Again, breaking line of sight and staying hidden for a minute or two will de-escalate the situation.