BattleTech

Check LOS using hex elevation and intervening terrain: light woods = 1 point, heavy woods = 2 points, and three or more points of intervening woods block LOS; water blocks LOS and intervening 'Mechs have no effect. Partial cover conceals but does not block LOS. (see p.16)

You may only fire weapons into their firing arcs (forward/left/right/rear); torso twists change the upper-body firing arcs for the turn, and reversing (flipping) arms lets arm-mounted weapons use the rear arc instead of their normal arcs. Rear‑mounted weapons fire only into the rear arc, and you cannot torso twist and reverse arms in the same turn — declare these during attack declaration. (see pp.16–17)

Track heat on the Heat Scale: at set thresholds you take movement and weapon-to-hit penalties, and at the shutdown thresholds you must roll to avoid an automatic shutdown; a shutdown makes the 'Mech immobile and disables most equipment until restarted. Heat sinks and water dissipate heat each Heat Phase. (see pp.39–40)

PSRs are required for events like falls, taking 20+ damage in a phase, losing leg/foot actuators, certain movement (jumps/standing in bad terrain), and more; roll 2D6 vs your Piloting Skill plus modifiers. Failing a PSR usually means the 'Mech falls (or otherwise suffers the listed consequence), and immobile or unconscious 'Mechs automatically fail. (see pp.42–43)

Apply damage to the location's armor first; once armor is gone additional damage goes to internal structure, and any internal-structure damage may trigger critical-hit checks (use the Determining Critical Hits table). If a location is destroyed, further damage transfers inward per the damage-transfer rules and ammunition may explode; critical-hit effects are applied as resolved. (see pp.32–34)

Roll on the Cluster Hits Table to determine how many missiles actually hit; SRMs resolve one hit-location roll per missile that hits, while LRMs group hits into 5-missile lots and you roll one hit location per 5 missiles (with any remainder as a smaller lot). Resolve each hit/group separately when applying damage. (see pp.25–26)