diff --git a/bin/common/Language/BOXCE/en-US.yml b/bin/common/Language/BOXCE/en-US.yml
index 8916396a6c..65342597ce 100644
--- a/bin/common/Language/BOXCE/en-US.yml
+++ b/bin/common/Language/BOXCE/en-US.yml
@@ -113,3 +113,6 @@ en-US:
   WRT_VANILLA: "vanilla formula"
   hangarType: "Hangar Type"
   spaceOccupied: "Space Occupied"
+  # Diagonal Terrain melee
+  STR_DIAG_TERRAIN_MELEE: "Diagonal Terrain Melee"
+  STR_DIAG_TERRAIN_MELEE_DESC: "Hitting terrain objects at diagonal directions with melee.{NEWLINE}Requires activated \"TerrainMeleeExtended\" feature.{NEWLINE}{ALT}Alt+click{ALT} - to hit objects at current and adjacent tiles."
\ No newline at end of file
diff --git a/bin/common/Language/BOXCE/ru.yml b/bin/common/Language/BOXCE/ru.yml
index e9a6a266ed..2053474080 100644
--- a/bin/common/Language/BOXCE/ru.yml
+++ b/bin/common/Language/BOXCE/ru.yml
@@ -111,3 +111,6 @@ ru:
   WRT_VANILLA: "Формула из оригинальной игры"
   hangarType: "Тип ангара"
   spaceOccupied: "Место занято"
+ # Diagonal Terrain melee
+  STR_DIAG_TERRAIN_MELEE: "Рукопашно местность по диагонали "
+  STR_DIAG_TERRAIN_MELEE_DESC: "Атака объектов ландшафта по диагонали в ближнем бою.{NEWLINE}Требует включения опции \"terrainMeleeExtended\".{NEWLINE}{ALT}Alt+клик{ALT} - бить объекты на текущей и соседних клетках."
diff --git a/src/Battlescape/TileEngine.cpp b/src/Battlescape/TileEngine.cpp
index e983ab2040..a1d321b178 100644
--- a/src/Battlescape/TileEngine.cpp
+++ b/src/Battlescape/TileEngine.cpp
@@ -3231,6 +3231,7 @@ TileEngine::ReactionScore TileEngine::determineReactionType(BattleUnit *unit, Ba
 				return reaction;
 			}
 		}
+
 		if (_save->canUseWeapon(weapon, unit, false, BA_SNAPSHOT))
 		{
 			// has a gun capable of snap shot with ammo
@@ -5947,7 +5948,7 @@ bool TileEngine::validTerrainMeleeRange(BattleAction* action)
 	action->terrainMeleeTilePart = 0;
 
 	if (action->weapon)
-	{
+	{	// is melee weapon able to hit terrain ?
 		auto wRule = action->weapon->getRules();
 		if (wRule->getBattleType() == BT_MELEE)
 		{
@@ -5961,79 +5962,115 @@ bool TileEngine::validTerrainMeleeRange(BattleAction* action)
 		}
 	}
 
-	Position pos = action->actor->getPosition();
 	int direction = action->actor->getDirection();
-	BattleUnit* attacker = action->actor;
 
 	if (direction < 0 || direction > 7)
-	{
+	{	// only horisontal direction are allowed
 		return false;
-	}
-	if (direction % 2 != 0)
+	} 
+	if (!Options::diagTerrainMelee && direction % 2 != 0)
 	{
-		// diagonal directions are not supported
+		// diagonal directions are not supported. pWWWa: if proper option is not activated
 		return false;
 	}
+
+	Position pos = action->actor->getPosition();
 	Position p;
 	Pathfinding::directionToVector(direction, &p);
-
 	Tile* originTile = _save->getTile(pos);
-	Tile* originTile2 = originTile;
-	if (originTile && originTile->getTerrainLevel() <= -16)
+
+	if (originTile && originTile->getTerrainLevel() <= -16 && !_save->isAltPressed(true))
 	{
-		// if we are on the upper part of stairs, target one tile above
+		// if we are on the upper part of stairs, target one tile above. pWWWa: let leave at the same tile altitude with pressed Alt (if there are need to hit stair under feet).
 		pos += Position(0, 0, 1);
 		originTile = _save->getTile(pos);
 	}
-	Tile* neighbouringTile = _save->getTile(pos + p);
-	Tile* neighbouringTile2 = nullptr;
-	int size = attacker->getArmor()->getSize();
-	if (size > 1)
+
+	Tile* originTile2 =			originTile;
+	Tile* neighbouringTile =	_save->getTile(pos + p);
+	Tile* neighbouringTile2 =	nullptr;
+	Tile* neighbouringTile3 =	nullptr;
+	int size = action->actor->getArmor()->getSize() - 1; // pWWWa: attacker variable removed, cause it used only once
+
+	switch (direction)
 	{
-		if (direction == 0)
-		{
-			// North
-			originTile2 = _save->getTile(pos + Position(1, 0, 0));
-			neighbouringTile2 = _save->getTile(pos + p + Position(1, 0, 0));
-		}
-		else if (direction == 2)
-		{
-			// East
-			neighbouringTile =  _save->getTile(pos + p + Position(1, 0, 0));
-			neighbouringTile2 = _save->getTile(pos + p + Position(1, 1, 0));
-		}
-		else if (direction == 4)
-		{
-			// South
-			neighbouringTile =  _save->getTile(pos + p + Position(0, 1, 0));
-			neighbouringTile2 = _save->getTile(pos + p + Position(1, 1, 0));
-		}
-		else if (direction == 6)
-		{
-			// West
-			originTile2 = _save->getTile(pos + Position(0, 1, 0));
-			neighbouringTile2 = _save->getTile(pos + p + Position(0, 1, 0));
-		}
-		if (!neighbouringTile2 || !originTile2)
-		{
-			return false;
-		}
+		case 0: // North
+				originTile2 =		_save->getTile(pos + Position(size, 0, 0));
+				neighbouringTile2 = _save->getTile(pos + p + Position(size, 0, 0));
+				break;
+
+		case 2: // East
+				originTile =		_save->getTile(pos + Position(size, 0, 0));
+				originTile2 =		_save->getTile(pos + Position(size, size, 0));
+				neighbouringTile =	_save->getTile(pos + p + Position(size, 0, 0));
+				neighbouringTile2 = _save->getTile(pos + p + Position(size, size, 0));
+				break;
+
+		case 4: // South
+				originTile =		_save->getTile(pos + Position(0, size, 0));
+				originTile2 =		_save->getTile(pos + Position(size, size, 0));
+				neighbouringTile =	_save->getTile(pos + p + Position(0, size, 0));
+				neighbouringTile2 = _save->getTile(pos + p + Position(size, size, 0));
+				break;
+
+		case 6: // West
+				originTile2 =		_save->getTile(pos + Position(0, size, 0));
+				neighbouringTile2 = _save->getTile(pos + p + Position(0, size, 0));
+				break;
+
+		case 1: // North-East
+				originTile =		_save->getTile(pos + Position(size, 0, 0));
+				neighbouringTile =	_save->getTile(pos + p + Position(size, 0, 0));		
+				neighbouringTile2 = _save->getTile(pos + Position(size, -1, 0));
+				neighbouringTile3 = _save->getTile(pos + Position(size + 1, 0, 0));
+				break;
+
+		case 3: // South-East
+				originTile =	    _save->getTile(pos + Position(size, size, 0));
+				neighbouringTile =  _save->getTile(pos + p + Position(size, size, 0));
+				neighbouringTile2 = _save->getTile(pos + p + Position(size, size - 1, 0));
+				neighbouringTile3 = _save->getTile(pos + p + Position(size - 1, size, 0));
+				break;
+
+		case 5: // South-West
+				originTile =		_save->getTile(pos + Position(0, size, 0));
+				neighbouringTile =	_save->getTile(pos + p + Position(0, size, 0));
+				neighbouringTile2 = _save->getTile(pos + Position(0, size + 1, 0));
+				neighbouringTile3 = _save->getTile(pos + Position(- 1, size, 0));
+				break;
+
+		case 7: //North-West
+				neighbouringTile2 = _save->getTile(pos + Position(-1, 0, 0));
+				neighbouringTile3 = _save->getTile(pos + Position(0, -1, 0));
 	}
+
 	if (originTile && neighbouringTile)
 	{
 		auto setTarget = [](Tile* tt, TilePart tp, BattleAction* aa, int dir = -1) -> bool
 		{
+			Position origin = tt->getSavedGame()->getTileEngine()->getSightOriginVoxel(aa->actor, tt) + Position(0, 0, -4);
+			Position target;
+
+			if (!tt->getSavedGame()->getTileEngine()->canTargetTile(&origin, tt, tp, &target, aa->actor, false))
+			{ // is tile reachable (more predictable targeting queue at diagonals)
+				return false;
+			}
+				
 			MapData* obj = tt->getMapData(tp);
 			if (obj)
 			{
-				if (dir > -1 && tp == O_OBJECT)
-				{
+				if (dir > -1 && tp == O_OBJECT && !(Options::diagTerrainMelee && tt->getSavedGame()->isAltPressed(true)))
+				{ 
 					auto bigWall = obj->getBigWall();
 					if (dir == 0 /*north*/ && bigWall != Pathfinding::BIGWALLNORTH && bigWall != Pathfinding::BIGWALLWESTANDNORTH) return false;
 					if (dir == 2 /*east */ && bigWall != Pathfinding::BIGWALLEAST  && bigWall != Pathfinding::BIGWALLEASTANDSOUTH) return false;
 					if (dir == 4 /*south*/ && bigWall != Pathfinding::BIGWALLSOUTH && bigWall != Pathfinding::BIGWALLEASTANDSOUTH) return false;
 					if (dir == 6 /*west */ && bigWall != Pathfinding::BIGWALLWEST  && bigWall != Pathfinding::BIGWALLWESTANDNORTH) return false;
-				}
+					if (dir == 1 /*NW   */ && bigWall != Pathfinding::BIGWALLNWSE) return false;
+					if (dir == 3 /*NE   */ && bigWall != Pathfinding::BIGWALLNESW  && bigWall != Pathfinding::BIGWALLEASTANDSOUTH) return false;
+					if (dir == 5 /*SE   */ && bigWall != Pathfinding::BIGWALLNWSE) return false;
+					if (dir == 7 /*SW   */ && bigWall != Pathfinding::BIGWALLNESW  && bigWall != Pathfinding::BIGWALLWESTANDNORTH) return false;
+				} 
 				if (tp != O_OBJECT && !obj->isDoor() && !obj->isUFODoor() && tt->getTUCost(tp, MT_WALK) != Pathfinding::INVALID_MOVE_COST)
 				{
 					// it is possible to walk through this (rubble) wall... no need to attack it
@@ -6058,76 +6095,88 @@ bool TileEngine::validTerrainMeleeRange(BattleAction* action)
 			return false;
 		};
 
-		if (setTarget(originTile, O_OBJECT, action, direction))
+		if (setTarget(originTile, O_OBJECT, action, direction) ||
+			setTarget(originTile2, O_OBJECT, action, direction))
 		{
 			// All directions: target the object (marked as big wall) on the current tile
 			return true;
 		}
-		if (size > 1)
+
+		switch (direction)
 		{
-			if (setTarget(originTile2, O_OBJECT, action, direction))
-			{
-				// All directions
+		case 0: // North
+				if (setTarget(originTile, O_NORTHWALL, action) ||
+					setTarget(originTile2, O_NORTHWALL, action) ||
+					setTarget(neighbouringTile2, O_WESTWALL, action) && size)
 				return true;
-			}
-		}
+				break;
 
-		if (direction == 0 && setTarget(originTile, O_NORTHWALL, action))
-		{
-			// North: target the north wall of the same tile
-			return true;
-		}
-		else if (direction == 2 && setTarget(neighbouringTile, O_WESTWALL, action))
-		{
-			// East: target the west wall of the neighbouring tile
-			return true;
-		}
-		else if (direction == 4 && setTarget(neighbouringTile, O_NORTHWALL, action))
-		{
-			// South: target the north wall of the neighbouring tile
-			return true;
-		}
-		else if (direction == 6 && setTarget(originTile, O_WESTWALL, action))
-		{
-			// West: target the west wall of the same tile
-			return true;
-		}
-		if (size > 1)
-		{
-			if (direction == 0 && setTarget(originTile2, O_NORTHWALL, action))
-			{
-				// North
+		case 2: // East
+				if (setTarget(neighbouringTile, O_WESTWALL, action) ||
+					setTarget(neighbouringTile2, O_WESTWALL, action) ||
+					setTarget(neighbouringTile2, O_NORTHWALL, action) && size)
 				return true;
-			}
-			else if (direction == 2 && setTarget(neighbouringTile2, O_WESTWALL, action))
-			{
-				// East
+				break;
+
+		case 4: // South
+				if (setTarget(neighbouringTile, O_NORTHWALL, action) ||
+					setTarget(neighbouringTile2, O_NORTHWALL, action) ||
+					setTarget(neighbouringTile2, O_WESTWALL, action) && size)
 				return true;
-			}
-			else if (direction == 4 && setTarget(neighbouringTile2, O_NORTHWALL, action))
-			{
-				// South
+				break;
+
+		case 6: // West
+				if (setTarget(originTile, O_WESTWALL, action) ||
+					setTarget(originTile2, O_WESTWALL, action) ||
+					setTarget(neighbouringTile2, O_NORTHWALL, action) && size)
 				return true;
-			}
-			else if (direction == 6 && setTarget(originTile2, O_WESTWALL, action))
-			{
-				// West
+				break;
+
+		case 1:	 // North-East
+				if (setTarget(neighbouringTile, O_WESTWALL, action) ||		// 3
+					setTarget(neighbouringTile3, O_NORTHWALL, action) ||	// 4
+					setTarget(originTile, O_NORTHWALL, action) ||			// 1
+					setTarget(neighbouringTile3, O_WESTWALL, action))		// 2
+				return true;
+				break;
+				
+		case 3: // South-East 
+				if (setTarget(neighbouringTile, O_WESTWALL, action) ||      // 3
+					setTarget(neighbouringTile, O_NORTHWALL, action) ||     // 4
+					setTarget(neighbouringTile3, O_NORTHWALL, action) ||	// 1
+					setTarget(neighbouringTile2, O_WESTWALL, action))		// 2
+				return true;
+				break;
+				
+		case 5: // North-East
+				if (setTarget(neighbouringTile, O_NORTHWALL, action) ||		// 4
+					setTarget(neighbouringTile2, O_NORTHWALL, action) ||    // 1
+					setTarget(neighbouringTile2, O_WESTWALL, action) ||		// 3
+					setTarget(originTile, O_WESTWALL, action))	 			// 2
+				return true;
+				break;
+
+		case 7: // North-West
+				if (setTarget(neighbouringTile3, O_WESTWALL, action) ||     // 4
+					setTarget(neighbouringTile2, O_NORTHWALL, action) ||	// 3
+					setTarget(originTile, O_NORTHWALL, action) ||			// 2
+					setTarget(originTile, O_WESTWALL, action))				// 1
 				return true;
-			}
 		}
 
-		if (setTarget(neighbouringTile, O_OBJECT, action))
-		{
-			// All directions: target the object on the neighbouring tile
+		if (setTarget(neighbouringTile, O_OBJECT, action) ||
+			setTarget(neighbouringTile2, O_OBJECT, action) && size && !(direction % 2))
+		{	
+			// All directions: target the object on the neighbouring tile  + big unit's second part at non-diagonal direction included
 			return true;
 		}
-		if (size > 1)
+
+		if ( _save->isAltPressed(true) && direction % 2 &&
+		   ( setTarget(neighbouringTile2, O_OBJECT, action) ||
+			 setTarget(neighbouringTile3, O_OBJECT, action) ) )
 		{
-			if (setTarget(neighbouringTile2, O_OBJECT, action))
-			{
-				// All directions
-				return true;
-			}
+			// Diagonal terrain object targeting helper. Suitable for hitting big walls and terrain stuff at adjacent tiles.
+			return true;
 		}
 	}
 
diff --git a/src/Engine/Options.cpp b/src/Engine/Options.cpp
index 0b484caef6..b00cce5678 100644
--- a/src/Engine/Options.cpp
+++ b/src/Engine/Options.cpp
@@ -569,16 +569,21 @@ void createOptionsOTHER()
 
 void createAdvancedOptionsOTHER()
 {
+	// OTHER options General
 	_info.push_back(OptionInfo(OPTION_OTHER, "showCraftHangar", &showCraftHangar, false, "STR_SHOW_CRAFT_HANGAR", "STR_GENERAL"));
-	_info.push_back(OptionInfo(OPTION_OTHER, "forcedAbsoluteCosts", &forcedAbsoluteCosts, false, "STR_FORCED_ABSOLUTE_COSTS", "STR_BATTLESCAPE"));
 
+	// OTHER options Geoscape
 	_info.push_back(OptionInfo(OPTION_OTHER, "dogfightAI", &dogfightAI, true, "STR_DOGFIGHTAI", "STR_GEOSCAPE"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "aggressiveRetaliation", &aggressiveRetaliation, true, "STR_AGGRESSIVERETALIATION", "STR_GEOSCAPE"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "displayHiddenAlienActivity", &displayHiddenAlienActivity, 0, "STR_DISPLAY_HIDDEN_ALIEN_ACTIVITY", "STR_GEOSCAPE"));
 
+	// OTHER options Basescape
 	_info.push_back(OptionInfo(OPTION_OTHER, "baseDefenseProbability", &baseDefenseProbability, false, "STR_DISPLAY_BASE_DEFENSE_PROBABILITY", "STR_BASESCAPE"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "baseDetectionProbability", &baseDetectionProbability, false, "STR_DISPLAY_BASE_DETECTION_PROBABILITY", "STR_BASESCAPE"));
 
+	// OTHER options Battlescape
+	_info.push_back(OptionInfo(OPTION_OTHER, "diagTerrainMelee", &diagTerrainMelee, false, "STR_DIAG_TERRAIN_MELEE", "STR_BATTLESCAPE"));
+	_info.push_back(OptionInfo(OPTION_OTHER, "forcedAbsoluteCosts", &forcedAbsoluteCosts, false, "STR_FORCED_ABSOLUTE_COSTS", "STR_BATTLESCAPE"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "shootingSpreadMode", &shootingSpreadMode, 1, "STR_SHOOTING_SPREAD_MODE", "STR_BATTLESCAPE"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "useChanceToHit", &useChanceToHit, true, "STR_BATTLECHANCETOHIT", "STR_BATTLESCAPE"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "battleRealisticAccuracy", &battleRealisticAccuracy, false, "STR_BATTLEREALISTICACCURACY", "STR_BATTLESCAPE"));
@@ -599,6 +604,7 @@ void createAdvancedOptionsOTHER()
 	_info.push_back(OptionInfo(OPTION_OTHER, "preprimeGrenades", &preprimeGrenades, 1, "STR_PREPRIMEGRENADES", "STR_BATTLESCAPE"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "updateTurnsSinceSeenByClue", &updateTurnsSinceSeenByClue, true, "STR_UPDATETURNSSINCESEENBYCLUE", "STR_BATTLESCAPE"));
 
+	// OTHER options AI
 	_info.push_back(OptionInfo(OPTION_OTHER, "brutalAI", &brutalAI, 1, "STR_BRUTALAI", "STR_AI"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "brutalCivilians", &brutalCivilians, 0, "STR_BRUTALCIVILIANS", "STR_AI"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "ignoreDelay", &ignoreDelay, true, "STR_IGNOREDELAY", "STR_AI"));
@@ -606,6 +612,8 @@ void createAdvancedOptionsOTHER()
 	_info.push_back(OptionInfo(OPTION_OTHER, "avoidMines", &avoidMines, true, "STR_AVOIDMINES", "STR_AI"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "aiPeformance", &aiPerformanceOptimization, false, "STR_AI_PERFORMANCE", "STR_AI"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "aiCheatMode", &aiCheatMode, 0, "STR_AICHEATMODE", "STR_AI"));
+
+	// OTHER options Autoplay
 	_info.push_back(OptionInfo(OPTION_OTHER, "autoCombat", &autoCombat, false, "STR_AUTOCOMBAT", "STR_AUTO"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "autoCombatEachCombat", &autoCombatEachCombat, true, "STR_AUTOCOMBAT_EACH_COMBAT", "STR_AUTO"));
 	_info.push_back(OptionInfo(OPTION_OTHER, "autoCombatEachTurn", &autoCombatEachTurn, true, "STR_AUTOCOMBAT_EACH_TURN", "STR_AUTO"));
diff --git a/src/Engine/Options.inc.h b/src/Engine/Options.inc.h
index a4a1e514be..35d9c66a0d 100644
--- a/src/Engine/Options.inc.h
+++ b/src/Engine/Options.inc.h
@@ -36,7 +36,7 @@ OPT PathPreview battleNewPreviewPath;
 OPT int shootingSpreadMode, battleRealisticShotDispersion, battleRealisticCoverEfficiency, battleScrollSpeed, battleDragScrollButton, battleFireSpeed, battleXcomSpeed, battleAlienSpeed, battleExplosionHeight, battlescapeScale, battleTerrainSquishyness, preprimeGrenades, battleThrownSpeed;
 OPT bool traceAI, battleInstantGrenade, battleNotifyDeath, battleTooltips, battleHairBleach, battleAutoEnd,
 	strafe, forceFire, showMoreStatsInInventoryView, allowPsionicCapture, skipNextTurnScreen, disableAutoEquip, battleDragScrollInvert,
-	battleUFOExtenderAccuracy, useChanceToHit, battleRealisticAccuracy, battleRealisticImprovedAimed, battleRealisticImprovedLof, battleRealisticDisplayRolls, battleRealisticDisplayOthersRolls, battleAltGrenades, battleConfirmFireMode, battleSmoothCamera, noAlienPanicMessages, alienBleeding, instantPrime, strictBlockedChecking, updateTurnsSinceSeenByClue;
+	battleUFOExtenderAccuracy, useChanceToHit, battleRealisticAccuracy, battleRealisticImprovedAimed, battleRealisticImprovedLof, battleRealisticDisplayRolls, battleRealisticDisplayOthersRolls, battleAltGrenades, battleConfirmFireMode, battleSmoothCamera, noAlienPanicMessages, alienBleeding, instantPrime, strictBlockedChecking, updateTurnsSinceSeenByClue, diagTerrainMelee;
 OPT SDLKey keyBattleLeft, keyBattleRight, keyBattleUp, keyBattleDown, keyBattleLevelUp, keyBattleLevelDown, keyBattleCenterUnit, keyBattlePrevUnit, keyBattleNextUnit, keyBattleDeselectUnit,
 keyBattleUseLeftHand, keyBattleUseRightHand, keyBattleInventory, keyBattleMap, keyBattleOptions, keyBattleEndTurn, keyBattleAbort, keyBattleStats, keyBattleKneel,
 keyBattleReserveKneel, keyBattleReload, keyBattlePersonalLighting, keyBattleReserveNone, keyBattleReserveSnap, keyBattleReserveAimed, keyBattleReserveAuto,