Every weapon hit on a 'Mech does damage. Damage is first applied to the armor of the location hit, then internal structure. Every time a location's internal structure is damaged there is a chance for critical hits. Every damaging hit follows the below process:
1. Armor is reduced until zero, with remaining damage applied to internal structure. Torso armor has different front and rear values.
2. Internal structure is reduced until zero, then the location is destroyed. While the torso has different front and rear armor values, there are only single values for the internal structure of each torso. Once structure is damaged that location will start smoking. All components within a destroyed location are lost. Any further damage to that location transfers inwards, but the destroyed location absorbs 60% of the damage.
- Damage to a destroyed leg or arm transfers to the front side torso
- Damage to a destroyed side torso transfers to the front center torso
3. Every hit that damages internal structure has a chance to do critical damage ("crits"), causing bonus structure damage and damage to components. See Critical Hits for more information.
4. If there is ammunition within a location when the location is destroyed, there is the same chance for it to explode as if each ammunition bin was directly destroyed by critical damage. Gauss rifles also have a chance to explode when destroyed. See Armor/Structure for more information.
You can see out of your cockpit in three modes: visible, heat vision and night vision. Heat and night have less range than visible (which is infinite). Don't just blindly fire at the enemy, aim where they are already injured. On the battlefield use your sensors and target the enemy (default key "R") and see details of an enemy 'Mech. The left side shows the weapon load out and their current status (healthy or destroyed). The bottom shows the 'Mech chassis and variant. The majority displays the enemy 'Mech armor and structure status - armor is the thin line on the outside of each location, structure is the larger, internal block. The more red armor/structure is, the more damage it has received.
The further away the enemy is the longer it will take to see these details. If an enemy is near ECM it will take even longer and your sensor range is reduced. See Information Warfare for more information.
As you gain experience you will learn the hardpoints of the different chassis and use this knowledge to engage them. For example, the ballistic hardpoint on the AS7 Atlas is always in its right torso. Information is ammunition!
How to Destroy a 'Mech
There are three ways to destroy a BattleMech: Destroy both legs, destroy the engine or destroy the cockpit.
To destroy both legs you must remove the armor and internal structure from both legs. After destruction additional leg damage does not transfer from one leg to the other leg; additional leg damage transfers to the front side torso.
To destroy a 'Mech engine at least three slots must be lost. Removing the center torso destroys all engines since they occupy five slots in the center torso. See Movement for details.
While much harder to do, it takes far less damage to kill the pilot by destroying the 'Mech's cockpit. On most 'Mechs this is within what could be called its "head", but there are exceptions.
New Player Guide, Part Three: Playing MWO