MegaMek · exeea · Sep 10, 2026 · Sep 10, 2026 · Sep 10, 2026 · Sep 10, 2026
@@ -2450,6 +2450,8 @@ DeploymentDisplay.deployHullDown=Hull Down
 DeploymentDisplay.deployHullDownOff=Cancel Hull Down
 DeploymentDisplay.deployHullDown.tooltip=Toggle whether this vehicle starts the game hull down. Hull down requires deploying onto a fortified hex; turn it off here if you have no fortified hex to deploy into.
 DeploymentDisplay.deployTurn=Turn
+DeploymentDisplay.deployTurn.tooltip=Place the unit, then click a hex in the direction it should face. You can also hold Shift and drag. Buildings rotate their entire footprint around the origin hex.
+DeploymentDisplay.buildingCannotRotate=The building cannot fit at that facing. Its entire footprint must fit on valid hexes within the deployment zone. Choose another direction or move the building.
 DeploymentDisplay.deployFacing=Facing
 DeploymentDisplay.deployLoad=Load
 DeploymentDisplay.deployUnload=Unload
@@ -3954,6 +3956,11 @@ MovementDisplay.moveShakeOff=Shake Off
 MovementDisplay.MoveTakeOff=Lift Off
 MovementDisplay.moveTakeCover=Take Cover
 MovementDisplay.moveTow=Tow
+MovementDisplay.moveModuleLink=Link Modules
+MovementDisplay.moveModuleUnlink=Unlink Modules
+MovementDisplay.ModulePartner=Choose the adjacent module whose linkages to engage or detach.
+CommonMenuBar.moveModuleLink=Link Modules
+CommonMenuBar.moveModuleUnlink=Unlink Modules
 MovementDisplay.moveTurn=Turn
 MovementDisplay.MoveTurnLeft=Turn Left
 MovementDisplay.MoveTurnRight=Turn Right
@@ -7386,3 +7393,10 @@ ForceGeneratorDialog.formationDropped=A {0} formation could not be built here.\n
 
 # SearchableComboBox
 SearchableComboBox.tooltip=Type to search the list, Enter picks the highlighted or first match, Escape clears the search
+BuildingCriticalWeaponDialog.title=Building Critical Hit
+BuildingCriticalWeaponDialog.message=The critical-hit roll gives you the choice. Select the affected weapon.
+MovementDisplay.MobileAvoidance=Collision avoided: plot your full walking or cruising move now, then press Done. The Mobile Structure will continue afterward.
+MovementDisplay.MobileAvoidanceWalk=Collision avoidance permits walking or cruising movement only.
+MovementDisplay.MobilePivot=Choose the central pivot hex
+MovementDisplay.MobileSpeedTitle=Water Mobile Structure speed
+MovementDisplay.MobileSpeed=Choose this turn's speed (MP). Unplotted movement continues in the last travel direction.
@@ -163,6 +163,7 @@ BuildingType.MEDIUM.text=Medium
 BuildingType.HEAVY.text=Heavy
 BuildingType.HARDENED.text=Hardened
 BuildingType.WALL.text=Wall
+BuildingType.RAIL.text=Rail
 ##### Unsorted Resources
 #Aerospace Critical Damage Strings
 Aero.avionicsDamageString=Avionics (%d)

@@ -242,6 +242,10 @@ GameOptionsInfo.option.assault_drop.description=If checked, Meks, ProtoMeks and
 GameOptionsInfo.option.paratroopers.displayableName=(Legacy) Paratroopers
 GameOptionsInfo.option.paratroopers.description=If checked, infantry can deploy using assault drop rules (assault drop must also be enabled).
 GameOptionsInfo.option.bridge_building_engineers.displayableName=TO Bridge-Building Engineers (Infantry)
+GameOptionsInfo.option.building_expanded_cf.displayableName=TO Optional Building Damage Tracking (Expanded CF)
+GameOptionsInfo.option.building_expanded_collapse.displayableName=TO Expanded Building Collapse
+GameOptionsInfo.option.building_expanded_collapse.description=Collapsing structures damage adjacent parts of the same building and scatter debris into nearby hexes. This is independent of per-floor CF tracking (TO:AR pp. 121-123).
+GameOptionsInfo.option.building_expanded_cf.description=Track CF and armor separately on each floor of buildings and Mobile Structures. When disabled, damage is tracked per hex. All players must agree to this optional rule before play begins (TO:AR pp. 119-121; TO:AUE p. 40, Optional Damage Tracking).
 GameOptionsInfo.option.bridge_building_engineers.description=If checked, infantry with the Bridge-Building Engineers specialization can spend 6 full turns adjacent to a target hex to raise a single-hex Light Bridge (CF 15, two per scenario) or Medium Bridge (CF 40, one per scenario). CF is doubled when the bridge is built over water. Taking casualties during construction extends the work by 1 turn. TO:AUE.
 GameOptionsInfo.option.unofficial_bridge_repair_engineers.displayableName=(Unofficial) Bridge-Building Engineers May Repair Destroyed Sections
 GameOptionsInfo.option.unofficial_bridge_repair_engineers.description=Requires the TO Bridge-Building Engineers option. If checked, a Bridge-Building Engineer platoon may also rebuild a single destroyed section (a missing hex) of an existing bridge by working from an adjacent surviving span or bank, using the normal build rules. The player chooses a Light (CF 15) or Medium (CF 40) section, doubled over water, costing bridge-building points by type (Light 1, Medium both); the new section's deck matches the surviving span so the bridge reconnects. Rubble left under the collapsed section remains. This is a house rule, not part of any published BattleTech ruleset.

@@ -919,6 +919,11 @@
 5297=Industrial elevator at <data> moves <data> from level <data> to level <data>.
 5298=<data> fell down elevator shaft!
 5299=<data> rides elevator <data> to level <data>.
+9891=<data> commits <data> of <data> MP toward its next maneuver; its footprint has not moved yet.
+9895=<data> cannot complete this move: collision resolution between Mobile Structures is not yet supported. The colliding step was not applied.
+9892=<data> checks environmental integrity at <data>: roll <data>, modifier <data>; <msg:9893,9894>.
+9893=breached
+9894=seal holds
 5300=<data> (<data>) digs in and takes cover.
 5301=<data> (<data>) hits the deck.
 5305=<data> (<data>) builds fortifications in hex <data>
@@ -1687,3 +1692,5 @@ report.unknownOwner=Unknown owner
 7722=\ no ignition.
 7723=<data> (<data>) needs <data>+ for its exhaust to set the hexes behind hex <data> alight as it lands, rolled <data> :<msg:7721,7722>
 7724=\ The flammable atmosphere spreads this attack across the platoon as an area-effect attack: <data> damage.
+9896=<data> suffers <data> armor and <data> CF damage; <data> CF remains on this segment.
+9897=<data> is lost to <data> and begins sinking next turn at <data> depths per turn. Units on its deck and in its bays remain aboard.
@@ -555,6 +555,10 @@ public void sendBuildingEdit(BuildingEditSpec spec) {
         send(new Packet(PacketCommand.BUILDING_EDIT, spec));
     }
 
+    public void sendBuildingDoor(int buildingId, int doorIndex, boolean open) {
+        send(new Packet(PacketCommand.BUILDING_DOOR, buildingId, doorIndex, open));
+    }
+
     /**
      * Sends a packet containing multiple entity updates. Should only be used in the lobby phase.
      */
@@ -864,7 +868,13 @@ protected void receiveBuildingRemove(Packet packet) throws InvalidPacketDataExce
 
     protected void receiveBuildingCollapse(Packet packet) throws InvalidPacketDataException {
         int boardId = packet.getIntValue(1);
-        game.getBoard(boardId).collapseBuilding(packet.getCoordsVector(0));
+        if (packet.getObject(2) instanceof Integer entityId && game.getEntity(entityId) instanceof IBuilding building) {
+            for (Coords coords : packet.getCoordsVector(0)) {
+                game.getBoard(boardId).collapseBuilding(building, coords);
+            }
+        } else {
+            game.getBoard(boardId).collapseBuilding(packet.getCoordsVector(0));
+        }
     }
 
     /**
@@ -1437,6 +1447,9 @@ protected boolean handleGameSpecificPacket(Packet packet) {
                     if (cfrType != null) {
                         GameCFREvent cfrEvt = new GameCFREvent(this, cfrType);
                         switch (cfrType) {
+                            case CFR_MOBILE_AVOIDANCE:
+                                cfrEvt.setEntityId(packet.getIntValue(1));
+                                break;
                             case CFR_DOMINO_EFFECT:
                                 cfrEvt.setEntityId(packet.getIntValue(1));
                                 cfrEvt.setDirection(packet.getIntValue(2));
@@ -1463,6 +1476,10 @@ protected boolean handleGameSpecificPacket(Packet packet) {
                                 cfrEvt.setTAGTargets(packet.getIntList(1));
                                 cfrEvt.setTAGTargetTypes(packet.getIntList(2));
                                 break;
+                            case CFR_BUILDING_WEAPON:
+                                cfrEvt.setEntityId(packet.getIntValue(1));
+                                cfrEvt.setBuildingWeaponIds(packet.getIntList(2));
+                                break;
                             default:
                                 break;
                         }
@@ -1560,6 +1577,15 @@ public void sendTAGTargetCFRResponse(int index) {
         send(new Packet(PacketCommand.CLIENT_FEEDBACK_REQUEST, PacketCommand.CFR_TAG_TARGET, index));
     }
 
+    public void sendMobileAvoidanceCFRResponse(int entityId, MovePath path) {
+        send(new Packet(PacketCommand.CLIENT_FEEDBACK_REQUEST, PacketCommand.CFR_MOBILE_AVOIDANCE, entityId, path));
+    }
+
+    public void sendBuildingWeaponCFRResponse(int buildingId, int equipmentId) {
+        send(new Packet(PacketCommand.CLIENT_FEEDBACK_REQUEST, PacketCommand.CFR_BUILDING_WEAPON,
+              buildingId, equipmentId));
+    }
+
     public Set<BoardDimensions> getAvailableMapSizes() {
         return availableSizes;
     }
@@ -1670,6 +1696,10 @@ public void sendUnloadStranded(int... entityIds) {
         send(new Packet(PacketCommand.UNLOAD_STRANDED, entityIds));
     }
 
+    public void sendUnloadStranded(int[] entityIds, Map<Integer, Coords> exits) {
+        send(new Packet(PacketCommand.UNLOAD_STRANDED, entityIds, exits));
+    }
+
     /**
      * Change whose turn it is.
      */

@@ -353,6 +353,28 @@ public void gameClientFeedbackRequest(GameCFREvent evt) {
                     case CFR_TAG_TARGET:
                         sendTAGTargetCFRResponse(pickTagTarget(evt));
                         break;
+                    case CFR_BUILDING_WEAPON:
+                        sendBuildingWeaponCFRResponse(evt.getEntityId(), evt.getBuildingWeaponIds().getFirst());
+                        break;
+                    case CFR_MOBILE_AVOIDANCE:
+                        Entity avoiding = getGame().getEntity(evt.getEntityId());
+                        MovePath escape = new MovePath(getGame(), avoiding);
+                        for (int direction = 0; direction < 6; direction++) {
+                            MovePath candidate = new MovePath(getGame(), avoiding);
+                            candidate.findSimplePathTo(avoiding.getPosition().translated(direction,
+                                  Math.max(1, avoiding.getWalkMP())), megamek.common.enums.MoveStepType.FORWARDS,
+                                  direction, avoiding.getFacing());
+                            while (candidate.length() > 0 && (candidate.getMpUsed() > avoiding.getWalkMP()
+                                  || !candidate.getLastStep().isLegal(candidate))) {
+                                candidate.removeLastStep();
+                            }
+                            if (candidate.getFinalCoords().distance(avoiding.getPosition())
+                                  > escape.getFinalCoords().distance(avoiding.getPosition())) {
+                                escape = candidate;
+                            }
+                        }
+                        sendMobileAvoidanceCFRResponse(avoiding.getId(), escape);
+                        break;
                     default:
                         break;
                 }

@@ -41,8 +41,8 @@
 import megamek.common.Hex;
 import megamek.common.HexTarget;
 import megamek.common.LosEffects;
-import megamek.common.PartialCover;
 import megamek.common.Messages;
+import megamek.common.PartialCover;
 import megamek.common.Player;
 import megamek.common.RangeType;
 import megamek.common.TargetRollModifier;
@@ -74,7 +74,6 @@
 import megamek.common.planetaryConditions.IlluminationLevel;
 import megamek.common.planetaryConditions.PlanetaryConditions;
 import megamek.common.rolls.TargetRoll;
-import megamek.common.rules.core.CoreRulesManager;
 import megamek.common.rules.totalwarfare.TWRulesManager;
 import megamek.common.units.*;
 import megamek.common.weapons.Weapon;
@@ -1707,7 +1706,7 @@ protected boolean isSubCommander(final Entity entity) {
             // building, or infantry/BA that won't be killed off in one shot.
         }
         if ((damageFraction < 0.5)
-              || (target.getTargetType() == Targetable.TYPE_BUILDING)
+              || (Targetable.isBuildingType(target.getTargetType()))
               || (target.getTargetType() == Targetable.TYPE_HEX_CLEAR)
         ) {
             return 0;
@@ -3328,7 +3327,7 @@ public static double getMaxDamageAtRange(final Entity shooter,
                 weaponDamage = weaponType.getRackSize();
             } else if (weaponDamage == WeaponType.DAMAGE_VARIABLE && shooter.isConventionalInfantry()) {
             	ConvInfantry infantryShooter = (ConvInfantry) shooter;
-            	
+
             	weaponDamage = (int) Math.round(infantryShooter.getDamagePerTrooper() * infantryShooter.getShootingStrength());
             }
 

@@ -34,6 +34,7 @@
 
 package megamek.client.ui;
 
+import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.ListIterator;
@@ -63,6 +64,14 @@
 public class SharedUtility {
     private final static MMLogger LOGGER = MMLogger.create(SharedUtility.class);
 
+    /** Displays Mobile Structure quarter-points as MP, retaining integer text for other units. */
+    public static String formatMovementPoints(@Nullable Entity entity, int points) {
+        if (entity instanceof MobileStructure) {
+            return BigDecimal.valueOf(points).divide(BigDecimal.valueOf(4)).stripTrailingZeros().toPlainString();
+        }
+        return Integer.toString(points);
+    }
+
     public static String doPSRCheck(MovePath md) {
         return (String) doPSRCheck(md, true);
     }
@@ -515,7 +524,9 @@ private static Object doPSRCheck(MovePath md, boolean stringResult) {
                     bldg = board.getBuildingAt(curPos);
                 }
 
-                if (bldg != null) {
+                if (bldg != null && !(bldg instanceof AbstractBuildingEntity buildingEntity
+                      && buildingEntity.getBuildingRuntimeState().openPassage(buildingEntity, entity,
+                            lastPos, curPos, step.getElevation()))) {
                     rollTarget = entity.rollMovementInBuilding(bldg, distance, reason, overallMoveType);
                     SharedUtility.checkNag(rollTarget, nagReport, psrList);
                 }
@@ -595,7 +606,7 @@ private static Object doPSRCheck(MovePath md, boolean stringResult) {
 
             firstStep = false;
         }
-        
+
         // running with destroyed hip or gyro needs a check
         rollTarget = entity.checkRunningWithDamage(overallMoveType, md.getHexesMoved());
         checkNag(rollTarget, nagReport, psrList);

@@ -74,9 +74,9 @@
 import megamek.client.commands.*;
 import megamek.client.event.BoardViewEvent;
 import megamek.client.event.BoardViewListener;
-import megamek.client.ratgenerator.GenerationContext;
 import megamek.client.event.MekDisplayEvent;
 import megamek.client.event.MekDisplayListener;
+import megamek.client.ratgenerator.GenerationContext;
 import megamek.client.ui.Messages;
 import megamek.client.ui.clientGUI.audio.AudioService;
 import megamek.client.ui.clientGUI.audio.SoundManager;
@@ -3494,7 +3494,7 @@ public void gameClientFeedbackRequest(GameCFREvent gameCFREvent) {
                     Object[] options;
                     MovePath[] paths;
                     int optionType;
-                    if (Game.rulesManager.getRulesMovement().isDominoMoveLegal(direction, entity, stepForward, true) 
+                    if (Game.rulesManager.getRulesMovement().isDominoMoveLegal(direction, entity, stepForward, true)
                           && Game.rulesManager.getRulesMovement().isDominoMoveLegal(direction, entity, stepBackward,
                           false)) {
                         options = new Object[3];
@@ -3695,6 +3695,26 @@ public void gameClientFeedbackRequest(GameCFREvent gameCFREvent) {
                         client.sendHiddenPBSCFRResponse(null);
                     }
                     break;
+                case CFR_MOBILE_AVOIDANCE:
+                    if (!(client instanceof BotClient) && entity != null
+                          && getCurrentPanel() instanceof MovementDisplay movement) {
+                        movement.beginMobileCollisionAvoidance(entity.getId());
+                    } else if (!(client instanceof BotClient)) {
+                        client.sendMobileAvoidanceCFRResponse(gameCFREvent.getEntityId(), null);
+                    }
+                    break;
+                case CFR_BUILDING_WEAPON:
+                    Entity criticalBuilding = client.getGame().getEntity(gameCFREvent.getEntityId());
+                    List<Integer> criticalWeapons = gameCFREvent.getBuildingWeaponIds();
+                    List<String> criticalChoices = criticalWeapons.stream()
+                          .map(id -> id + ": " + criticalBuilding.getEquipment(id).getDesc()).toList();
+                    input = (String) JOptionPane.showInputDialog(frame,
+                          Messages.getString("BuildingCriticalWeaponDialog.message"),
+                          Messages.getString("BuildingCriticalWeaponDialog.title"),
+                          JOptionPane.QUESTION_MESSAGE, null, criticalChoices.toArray(), criticalChoices.getFirst());
+                    client.sendBuildingWeaponCFRResponse(criticalBuilding.getId(),
+                          criticalWeapons.get(Math.max(0, criticalChoices.indexOf(input))));
+                    break;
                 case CFR_TELEGUIDED_TARGET:
                     logger.debug("CFR_TELEGUIDED_TARGET: processing teleguided missile target selection");
                     List<Integer> targetIds = gameCFREvent.getTelemissileTargetIds();