They can deal a lot of damage and fill a role similar to a melee unit.
They'll charge straight at an opponent regardless of the damage they're taking.
For example, soldiers on an assault might exchange attack slots rapidly to keep a constant stream of fire at an opponent. Squad slots can also be exchanged rapidly. This means a squad could potentially split up and attack different targets, but this all depends on who each squad member is prioritizing (which is influenced by distance, relationship strength, enemy filters, and who attacked the npc last). Worthy to note is that squad slots are handled per enemy. If a soldier is not using a squad slot they'll take cover. For difficulty reasons, whenever these slots are used they'll stop the entire squad from committing similar attacks for a period of time. SQUAD_SLOT_GRENADE1 and SQUAD_SLOT_SPECIAL_ATTACK are used by soldiers to throw grenades or launch energy balls. For more information, npc_combine.cpp has good notes. It is used to for advanced AI techniques, such as providing covering fire when teammates reload or sitting and aiming at a players last visible location. After reading comments inside the Half-Life 2 source files, the use of the Overwatch slot comes to light. It seems that it only applies to squad leaders. SQUAD_SLOT_OVERWATCH is a strange squad slot that rarely comes into affect. They do this to breakable objects they can see through, such as crates held by the Gravity Gun or windows. SQUAD_SLOT_ATTACK_OCCLUDER is the slot a soldier occupies when shooting out an opponent's cover. This is intended behavior, but can cause problems in expansive tight environments. Over longer distances soldiers will advance regardless of squad slots, and soldiers can lose their attack slot while moving and shooting.
SQUAD_SLOT_ATTACK1 and SQUAD_SLOT_ATTACK2 are the slots soldiers must have to be able to shoot at an enemy or advance in most cases. An npc will typically hold a squad slot for the duration of a Schedule.Ĭombine squads have 6 primary squad slots: SQUAD_SLOT_ATTACK1, SQUAD_SLOT_ATTACK2, SQUAD_SLOT_ATTACK_OCCLUDER, SQUAD_SLOT_GRENADE1, SQUAD_SLOT_OVERWATCH, and SQUAD_SLOT_SPECIAL_ATTACK. They allow npcs to trade roles and take turns.
Squad slots are the way squad based npcs operate. They often work in squads together and flank the player by spreading around and using frag grenades. Combine Soldiers are regularly seen throughout the Half-Life 2 series, there are four variations, including the "Regular", "Elite", "Prison Guard" and "Shotgunner".