diff --git a/OpenRA.Game/Graphics/Minimap.cs b/OpenRA.Game/Graphics/Minimap.cs
index c766273883..f81c6860b4 100644
--- a/OpenRA.Game/Graphics/Minimap.cs
+++ b/OpenRA.Game/Graphics/Minimap.cs
@@ -20,11 +20,12 @@ namespace OpenRA.Graphics
 	{
 		public static Bitmap TerrainBitmap(TileSet tileset, Map map, bool actualSize = false)
 		{
-			var width = map.Bounds.Width;
-			var height = map.Bounds.Height;
+			var b = map.Bounds;
+			var width = b.Width;
+			var height = b.Height;
 
 			if (!actualSize)
-				width = height = Exts.NextPowerOf2(Math.Max(map.Bounds.Width, map.Bounds.Height));
+				width = height = Exts.NextPowerOf2(Math.Max(b.Width, b.Height));
 
 			var terrain = new Bitmap(width, height);
 
@@ -37,15 +38,17 @@ namespace OpenRA.Graphics
 			{
 				var c = (int*)bitmapData.Scan0;
 
-				for (var x = 0; x < map.Bounds.Width; x++)
-					for (var y = 0; y < map.Bounds.Height; y++)
+				for (var x = 0; x < b.Width; x++)
+				{
+					for (var y = 0; y < b.Height; y++)
 					{
-						var mapX = x + map.Bounds.Left;
-						var mapY = y + map.Bounds.Top;
+						var mapX = x + b.Left;
+						var mapY = y + b.Top;
 						var type = tileset.GetTerrainInfo(mapTiles[mapX, mapY]);
 
 						*(c + (y * bitmapData.Stride >> 2) + x) = type.Color.ToArgb();
 					}
+				}
 			}
 
 			terrain.UnlockBits(bitmapData);
@@ -57,6 +60,7 @@ namespace OpenRA.Graphics
 		static Bitmap AddStaticResources(TileSet tileset, Map map, Ruleset resourceRules, Bitmap terrainBitmap)
 		{
 			var terrain = new Bitmap(terrainBitmap);
+			var b = map.Bounds;
 
 			var bitmapData = terrain.LockBits(terrain.Bounds(),
 				ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
@@ -65,11 +69,12 @@ namespace OpenRA.Graphics
 			{
 				var c = (int*)bitmapData.Scan0;
 
-				for (var x = 0; x < map.Bounds.Width; x++)
-					for (var y = 0; y < map.Bounds.Height; y++)
+				for (var x = 0; x < b.Width; x++)
+				{
+					for (var y = 0; y < b.Height; y++)
 					{
-						var mapX = x + map.Bounds.Left;
-						var mapY = y + map.Bounds.Top;
+						var mapX = x + b.Left;
+						var mapY = y + b.Top;
 						if (map.MapResources.Value[mapX, mapY].Type == 0)
 							continue;
 
@@ -82,6 +87,7 @@ namespace OpenRA.Graphics
 
 						*(c + (y * bitmapData.Stride >> 2) + x) = tileset[tileset.GetTerrainIndex(res)].Color.ToArgb();
 					}
+				}
 			}
 
 			terrain.UnlockBits(bitmapData);
@@ -92,7 +98,9 @@ namespace OpenRA.Graphics
 		public static Bitmap CustomTerrainBitmap(World world)
 		{
 			var map = world.Map;
-			var size = Exts.NextPowerOf2(Math.Max(map.Bounds.Width, map.Bounds.Height));
+			var b = map.Bounds;
+
+			var size = Exts.NextPowerOf2(Math.Max(b.Width, b.Height));
 			var bitmap = new Bitmap(size, size);
 			var bitmapData = bitmap.LockBits(bitmap.Bounds(),
 				ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
@@ -101,16 +109,19 @@ namespace OpenRA.Graphics
 			{
 				var c = (int*)bitmapData.Scan0;
 
-				for (var x = 0; x < map.Bounds.Width; x++)
-					for (var y = 0; y < map.Bounds.Height; y++)
+				for (var x = 0; x < b.Width; x++)
+				{
+					for (var y = 0; y < b.Height; y++)
 					{
-						var mapX = x + map.Bounds.Left;
-						var mapY = y + map.Bounds.Top;
+						var mapX = x + b.Left;
+						var mapY = y + b.Top;
 						var custom = map.CustomTerrain[mapX, mapY];
 						if (custom == -1)
 							continue;
+
 						*(c + (y * bitmapData.Stride >> 2) + x) = world.TileSet[custom].Color.ToArgb();
 					}
+				}
 			}
 
 			bitmap.UnlockBits(bitmapData);
@@ -120,7 +131,9 @@ namespace OpenRA.Graphics
 		public static Bitmap ActorsBitmap(World world)
 		{
 			var map = world.Map;
-			var size = Exts.NextPowerOf2(Math.Max(map.Bounds.Width, map.Bounds.Height));
+			var b = map.Bounds;
+
+			var size = Exts.NextPowerOf2(Math.Max(b.Width, b.Height));
 			var bitmap = new Bitmap(size, size);
 			var bitmapData = bitmap.LockBits(bitmap.Bounds(),
 				ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
@@ -136,8 +149,11 @@ namespace OpenRA.Graphics
 
 					var color = t.Trait.RadarSignatureColor(t.Actor);
 					foreach (var cell in t.Trait.RadarSignatureCells(t.Actor))
-						if (world.Map.Contains(cell))
-							*(c + ((cell.Y - world.Map.Bounds.Top) * bitmapData.Stride >> 2) + cell.X - world.Map.Bounds.Left) = color.ToArgb();
+					{
+						var uv = Map.CellToMap(map.TileShape, cell);
+						if (b.Contains(uv.X, uv.Y))
+							*(c + ((uv.Y - b.Top) * bitmapData.Stride >> 2) + uv.X - b.Left) = color.ToArgb();
+					}
 				}
 			}
 
@@ -148,7 +164,9 @@ namespace OpenRA.Graphics
 		public static Bitmap ShroudBitmap(World world)
 		{
 			var map = world.Map;
-			var size = Exts.NextPowerOf2(Math.Max(map.Bounds.Width, map.Bounds.Height));
+			var b = map.Bounds;
+
+			var size = Exts.NextPowerOf2(Math.Max(b.Width, b.Height));
 			var bitmap = new Bitmap(size, size);
 			if (world.RenderPlayer == null)
 				return bitmap;
@@ -158,20 +176,20 @@ namespace OpenRA.Graphics
 
 			var shroud = Color.Black.ToArgb();
 			var fog = Color.FromArgb(128, Color.Black).ToArgb();
+			var offset = new CVec(b.Left, b.Top);
 
 			unsafe
 			{
 				var c = (int*)bitmapData.Scan0;
 
-				for (var x = 0; x < map.Bounds.Width; x++)
-					for (var y = 0; y < map.Bounds.Height; y++)
-					{
-						var p = new CPos(x + map.Bounds.Left, y + map.Bounds.Top);
-						if (world.ShroudObscures(p))
-							*(c + (y * bitmapData.Stride >> 2) + x) = shroud;
-						else if (world.FogObscures(p))
-							*(c + (y * bitmapData.Stride >> 2) + x) = fog;
-					}
+				foreach (var cell in map.Cells)
+				{
+					var uv = Map.CellToMap(map.TileShape, cell) - offset;
+					if (world.ShroudObscures(cell))
+						*(c + (uv.Y * bitmapData.Stride >> 2) + uv.X) = shroud;
+					else if (world.FogObscures(cell))
+						*(c + (uv.Y * bitmapData.Stride >> 2) + uv.X) = fog;
+				}
 			}
 
 			bitmap.UnlockBits(bitmapData);
diff --git a/OpenRA.Game/Graphics/TerrainRenderer.cs b/OpenRA.Game/Graphics/TerrainRenderer.cs
index 11dc2f142d..c194be88e3 100644
--- a/OpenRA.Game/Graphics/TerrainRenderer.cs
+++ b/OpenRA.Game/Graphics/TerrainRenderer.cs
@@ -44,11 +44,12 @@ namespace OpenRA.Graphics
 		{
 			var verticesPerRow = 4*map.Bounds.Width;
 			var cells = viewport.VisibleCells;
-			var firstRow = cells.TopLeft.Y - map.Bounds.Top;
-			var lastRow = cells.BottomRight.Y - map.Bounds.Top + 1;
+			var shape = wr.world.Map.TileShape;
 
-			if (lastRow < 0 || firstRow > map.Bounds.Height)
-				return;
+			// Only draw the rows that are visible.
+			// VisibleCells is clamped to the map, so additional checks are unnecessary
+			var firstRow = Map.CellToMap(shape, cells.TopLeft).Y - map.Bounds.Top;
+			var lastRow = Map.CellToMap(shape, cells.BottomRight).Y - map.Bounds.Top + 1;
 
 			Game.Renderer.WorldSpriteRenderer.DrawVertexBuffer(
 				vertexBuffer, verticesPerRow * firstRow, verticesPerRow * (lastRow - firstRow),
diff --git a/OpenRA.Game/Graphics/Viewport.cs b/OpenRA.Game/Graphics/Viewport.cs
index 3c181f6480..383f6df1d7 100644
--- a/OpenRA.Game/Graphics/Viewport.cs
+++ b/OpenRA.Game/Graphics/Viewport.cs
@@ -92,8 +92,8 @@ namespace OpenRA.Graphics
 			var b = map.Bounds;
 
 			// Expand to corners of cells
-			var tl = wr.ScreenPxPosition(map.CenterOfCell(new CPos(b.Left, b.Top)) - new WVec(512, 512, 0));
-			var br = wr.ScreenPxPosition(map.CenterOfCell(new CPos(b.Right, b.Bottom)) + new WVec(511, 511, 0));
+			var tl = wr.ScreenPxPosition(map.CenterOfCell(Map.MapToCell(map.TileShape, new CPos(b.Left, b.Top))) - new WVec(512, 512, 0));
+			var br = wr.ScreenPxPosition(map.CenterOfCell(Map.MapToCell(map.TileShape, new CPos(b.Right, b.Bottom))) + new WVec(511, 511, 0));
 			mapBounds = Rectangle.FromLTRB(tl.X, tl.Y, br.X, br.Y);
 
 			CenterLocation = (tl + br) / 2;
@@ -138,8 +138,13 @@ namespace OpenRA.Graphics
 		{
 			get
 			{
-				var ctl = worldRenderer.world.Map.CenterOfCell(VisibleCells.TopLeft) - new WVec(512, 512, 0);
-				var cbr = worldRenderer.world.Map.CenterOfCell(VisibleCells.BottomRight) + new WVec(511, 511, 0);
+				// Visible rectangle in world coordinates (expanded to the corners of the cells)
+				// Expand the cordon by an additional cell to account for staggered rows on diamond cell grids.
+				var map = worldRenderer.world.Map;
+				var ctl = map.CenterOfCell(VisibleCells.TopLeft) - new WVec(1536, 1536, 0);
+				var cbr = map.CenterOfCell(VisibleCells.BottomRight) + new WVec(1535, 1535, 0);
+
+				// Convert to screen coordinates
 				var tl = WorldToViewPx(worldRenderer.ScreenPxPosition(ctl)).Clamp(ScreenClip);
 				var br = WorldToViewPx(worldRenderer.ScreenPxPosition(cbr)).Clamp(ScreenClip);
 				return Rectangle.FromLTRB(tl.X, tl.Y, br.X, br.Y);
@@ -152,12 +157,16 @@ namespace OpenRA.Graphics
 			{
 				if (cellsDirty)
 				{
-					// Calculate the intersection of the visible rectangle and the map.
+					// Visible rectangle in map coordinates
 					var map = worldRenderer.world.Map;
-					var tl = map.Clamp(map.CellContaining(worldRenderer.Position(TopLeft)) - new CVec(1, 1));
-					var br = map.Clamp(map.CellContaining(worldRenderer.Position(BottomRight)));
+					var ctl = Map.CellToMap(map.TileShape, map.CellContaining(worldRenderer.Position(TopLeft)));
+					var cbr = Map.CellToMap(map.TileShape, map.CellContaining(worldRenderer.Position(BottomRight)));
 
-					cells = new CellRegion(tl, br);
+					// Add a 2 cell cordon to prevent holes, then convert back to cell coordinates
+					var tl = map.Clamp(Map.MapToCell(map.TileShape, ctl - new CVec(2, 2)));
+					var br = map.Clamp(Map.MapToCell(map.TileShape, cbr + new CVec(2, 2)));
+
+					cells = new CellRegion(map.TileShape, tl, br);
 					cellsDirty = false;
 				}
 
diff --git a/OpenRA.Game/Manifest.cs b/OpenRA.Game/Manifest.cs
index 194dadca8c..ece91098dc 100644
--- a/OpenRA.Game/Manifest.cs
+++ b/OpenRA.Game/Manifest.cs
@@ -16,6 +16,8 @@ using OpenRA.Primitives;
 
 namespace OpenRA
 {
+	public enum TileShape { Rectangle, Diamond }
+
 	// Describes what is to be loaded in order to run a mod
 	public class Manifest
 	{
@@ -33,6 +35,7 @@ namespace OpenRA
 		public readonly Dictionary<string, Pair<string, int>> Fonts;
 		public readonly Size TileSize = new Size(24, 24);
 		public readonly string NewsUrl;
+		public readonly TileShape TileShape = TileShape.Rectangle;
 
 		public Manifest(string mod)
 		{
@@ -77,6 +80,9 @@ namespace OpenRA
 			if (yaml.ContainsKey("TileSize"))
 				TileSize = FieldLoader.GetValue<Size>("TileSize", yaml["TileSize"].Value);
 
+			if (yaml.ContainsKey("TileShape"))
+				TileShape = FieldLoader.GetValue<TileShape>("TileShape", yaml["TileShape"].Value);
+
 			// Allow inherited mods to import parent maps.
 			var compat = new List<string>();
 			compat.Add(mod);
diff --git a/OpenRA.Game/Map/CellLayer.cs b/OpenRA.Game/Map/CellLayer.cs
index 7f973b8902..3c0f444840 100644
--- a/OpenRA.Game/Map/CellLayer.cs
+++ b/OpenRA.Game/Map/CellLayer.cs
@@ -20,22 +20,24 @@ namespace OpenRA
 	public class CellLayer<T> : IEnumerable<T>
 	{
 		public readonly Size Size;
+		public readonly TileShape Shape;
 		T[] entries;
 
 		public CellLayer(Map map)
-			: this(new Size(map.MapSize.X, map.MapSize.Y)) { }
+			: this(map.TileShape, new Size(map.MapSize.X, map.MapSize.Y)) { }
 
-		public CellLayer(Size size)
+		public CellLayer(TileShape shape, Size size)
 		{
 			Size = size;
+			Shape = shape;
 			entries = new T[size.Width * size.Height];
 		}
 
 		// Resolve an array index from cell coordinates
 		int Index(CPos cell)
 		{
-			// This will eventually define a distinct case for diagonal cell grids
-			return cell.Y * Size.Width + cell.X;
+			var uv = Map.CellToMap(Shape, cell);
+			return uv.Y * Size.Width + uv.X;
 		}
 
 		/// <summary>Gets or sets the <see cref="OpenRA.CellLayer"/> using cell coordinates</summary>
@@ -90,7 +92,7 @@ namespace OpenRA
 		/// <summary>Create a new layer by resizing another layer.  New cells are filled with defaultValue.</summary>
 		public static CellLayer<T> Resize<T>(CellLayer<T> layer, Size newSize, T defaultValue)
 		{
-			var result = new CellLayer<T>(newSize);
+			var result = new CellLayer<T>(layer.Shape, newSize);
 			var width = Math.Min(layer.Size.Width, newSize.Width);
 			var height = Math.Min(layer.Size.Height, newSize.Height);
 
diff --git a/OpenRA.Game/Map/CellRegion.cs b/OpenRA.Game/Map/CellRegion.cs
index 3cdccc7fbe..282030b07f 100644
--- a/OpenRA.Game/Map/CellRegion.cs
+++ b/OpenRA.Game/Map/CellRegion.cs
@@ -23,25 +23,26 @@ namespace OpenRA
 		// Corners of the region
 		public readonly CPos TopLeft;
 		public readonly CPos BottomRight;
+		readonly TileShape shape;
 
 		// Corners in map coordinates
-		// Defined for forward compatibility with diagonal cell grids
+		// These will only equal TopLeft and BottomRight for TileShape.Rectangular
 		readonly CPos mapTopLeft;
 		readonly CPos mapBottomRight;
 
-		public CellRegion(CPos topLeft, CPos bottomRight)
+		public CellRegion(TileShape shape, CPos topLeft, CPos bottomRight)
 		{
+			this.shape = shape;
 			TopLeft = topLeft;
 			BottomRight = bottomRight;
 
-			mapTopLeft = TopLeft;
-			mapBottomRight = BottomRight;
+			mapTopLeft = Map.CellToMap(shape, TopLeft);
+			mapBottomRight = Map.CellToMap(shape, BottomRight);
 		}
 
 		public bool Contains(CPos cell)
 		{
-			// Defined for forward compatibility with diagonal cell grids
-			var uv = cell;
+			var uv = Map.CellToMap(shape, cell);
 			return uv.X >= mapTopLeft.X && uv.X <= mapBottomRight.X && uv.Y >= mapTopLeft.Y && uv.Y <= mapBottomRight.Y;
 		}
 
@@ -93,7 +94,7 @@ namespace OpenRA
 				v = r.mapTopLeft.Y;
 			}
 
-			public CPos Current { get { return new CPos(u, v); } }
+			public CPos Current { get { return Map.MapToCell(r.shape, new CPos(u, v)); } }
 			object IEnumerator.Current { get { return Current; } }
 			public void Dispose() { }
 		}
diff --git a/OpenRA.Game/Map/Map.cs b/OpenRA.Game/Map/Map.cs
index 8cbe791316..484362f138 100644
--- a/OpenRA.Game/Map/Map.cs
+++ b/OpenRA.Game/Map/Map.cs
@@ -76,6 +76,8 @@ namespace OpenRA
 		public bool AllowStartUnitConfig = true;
 		public Bitmap CustomPreview;
 
+		public readonly TileShape TileShape;
+
 		[FieldLoader.LoadUsing("LoadOptions")]
 		public MapOptions Options;
 
@@ -125,11 +127,12 @@ namespace OpenRA
 		public static Map FromTileset(TileSet tileset)
 		{
 			var size = new Size(1, 1);
+			var tileShape = Game.modData.Manifest.TileShape;
 			var tileRef = new TerrainTile(tileset.Templates.First().Key, (byte)0);
 
 			var makeMapTiles =  Exts.Lazy(() =>
 			{
-				var ret = new CellLayer<TerrainTile>(size);
+				var ret = new CellLayer<TerrainTile>(tileShape, size);
 				ret.Clear(tileRef);
 				return ret;
 			});
@@ -142,7 +145,7 @@ namespace OpenRA
 				MapSize = new int2(size),
 				Tileset = tileset.Id,
 				Options = new MapOptions(),
-				MapResources = Exts.Lazy(() => new CellLayer<ResourceTile>(size)),
+				MapResources = Exts.Lazy(() => new CellLayer<ResourceTile>(tileShape, size)),
 				MapTiles = makeMapTiles,
 				Actors = Exts.Lazy(() => new Dictionary<string, ActorReference>()),
 				Smudges = Exts.Lazy(() => new List<SmudgeReference>())
@@ -242,6 +245,7 @@ namespace OpenRA
 
 			MapTiles = Exts.Lazy(() => LoadMapTiles());
 			MapResources = Exts.Lazy(() => LoadResourceTiles());
+			TileShape = Game.modData.Manifest.TileShape;
 
 			// The Uid is calculated from the data on-disk, so
 			// format changes must be flushed to disk.
@@ -262,9 +266,9 @@ namespace OpenRA
 			rules = Exts.Lazy(() => Game.modData.RulesetCache.LoadMapRules(this));
 			cachedTileSet = Exts.Lazy(() => Rules.TileSets[Tileset]);
 
-			var tl = new CPos(Bounds.Left, Bounds.Top);
-			var br = new CPos(Bounds.Right - 1, Bounds.Bottom - 1);
-			Cells = new CellRegion(tl, br);
+			var tl = Map.MapToCell(TileShape, new CPos(Bounds.Left, Bounds.Top));
+			var br = Map.MapToCell(TileShape, new CPos(Bounds.Right - 1, Bounds.Bottom - 1));
+			Cells = new CellRegion(TileShape, tl, br);
 
 			CustomTerrain = new CellLayer<int>(this);
 			foreach (var cell in Cells)
@@ -465,17 +469,79 @@ namespace OpenRA
 
 		public bool Contains(CPos cell)
 		{
-			return Bounds.Contains(cell.X, cell.Y);
+			var uv = CellToMap(TileShape, cell);
+			return Bounds.Contains(uv.X, uv.Y);
 		}
 
-		public WPos CenterOfCell(CPos c)
+		public WPos CenterOfCell(CPos cell)
 		{
-			return new WPos(1024 * c.X + 512, 1024 * c.Y + 512, 0);
+			if (TileShape == TileShape.Rectangle)
+				return new WPos(1024 * cell.X + 512, 1024 * cell.Y + 512, 0);
+
+			// Convert from diamond cell position (x, y) to world position (u, v):
+			// (a) Consider the relationships:
+			//  - Center of origin cell is (512, 512)
+			//  - +x adds (512, 512) to world pos
+			//  - +y adds (-512, 512) to world pos
+			// (b) Therefore:
+			//  - ax + by adds (a - b) * 512 + 512 to u
+			//  - ax + by adds (a + b) * 512 + 512 to v
+			return new WPos(512 * (cell.X - cell.Y + 1), 512 * (cell.X + cell.Y + 1), 0);
 		}
 
 		public CPos CellContaining(WPos pos)
 		{
-			return new CPos(pos.X / 1024, pos.Y / 1024);
+			if (TileShape == TileShape.Rectangle)
+				return new CPos(pos.X / 1024, pos.Y / 1024);
+
+			// Convert from world position to diamond cell position:
+			// (a) Subtract (512, 512) to move the rotation center to the middle of the corner cell
+			// (b) Rotate axes by -pi/4
+			// (c) Add 512 to x (but not y) to realign the cell
+			// (d) Divide by 1024 to find final cell coords
+			var u = (pos.Y + pos.X - 512) / 1024;
+			var v = (pos.Y - pos.X) / 1024;
+			return new CPos(u, v);
+		}
+
+		public static CPos MapToCell(TileShape shape, CPos map)
+		{
+			if (shape == TileShape.Rectangle)
+				return map;
+
+			// Convert from rectangular map position to diamond cell position
+			//  - The staggered rows make this fiddly (hint: draw a diagram!)
+			// (a) Consider the relationships:
+			//  - +1u (even -> odd) adds (1, -1) to (x, y)
+			//  - +1v (even -> odd) adds (1, 0) to (x, y)
+			//  - +1v (odd -> even) adds (0, 1) to (x, y)
+			// (b) Therefore:
+			//  - au + 2bv adds (a + b) to (x, y)
+			//  - a correction factor is added if v is odd
+			var offset = (map.Y & 1) == 1 ? 1 : 0;
+			var y = (map.Y - offset) / 2 - map.X;
+			var x = map.Y - y;
+			return new CPos(x, y);
+		}
+
+		public static CPos CellToMap(TileShape shape, CPos cell)
+		{
+			if (shape == TileShape.Rectangle)
+				return cell;
+
+			// Convert from diamond cell (x, y) position to rectangular map position (u, v)
+			//  - The staggered rows make this fiddly (hint: draw a diagram!)
+			// (a) Consider the relationships:
+			//  - +1x (even -> odd) adds (0, 1) to (u, v)
+			//  - +1x (odd -> even) adds (1, 1) to (u, v)
+			//  - +1y (even -> odd) adds (-1, 1) to (u, v)
+			//  - +1y (odd -> even) adds (0, 1) to (u, v)
+			// (b) Therefore:
+			//  - ax + by adds (a - b)/2 to u (only even increments count)
+			//  - ax + by adds a + b to v
+			var u = (cell.X - cell.Y) / 2;
+			var v = cell.X + cell.Y;
+			return new CPos(u, v);
 		}
 
 		public int FacingBetween(CPos cell, CPos towards, int fallbackfacing)
@@ -497,7 +563,10 @@ namespace OpenRA
 		public void ResizeCordon(int left, int top, int right, int bottom)
 		{
 			Bounds = Rectangle.FromLTRB(left, top, right, bottom);
-			Cells = new CellRegion(new CPos(Bounds.Left, Bounds.Top), new CPos(Bounds.Right - 1, Bounds.Bottom - 1));
+
+			var tl = Map.MapToCell(TileShape, new CPos(Bounds.Left, Bounds.Top));
+			var br = Map.MapToCell(TileShape, new CPos(Bounds.Right - 1, Bounds.Bottom - 1));
+			Cells = new CellRegion(TileShape, tl, br);
 		}
 
 		string ComputeHash()
@@ -597,17 +666,18 @@ namespace OpenRA
 			return cachedTileSet.Value[GetTerrainIndex(cell)];
 		}
 
-		public CPos Clamp(CPos xy)
+		public CPos Clamp(CPos cell)
 		{
-			var r = Bounds;
-			return xy.Clamp(new Rectangle(r.X, r.Y, r.Width - 1, r.Height - 1));
+			var bounds = new Rectangle(Bounds.X, Bounds.Y, Bounds.Width - 1, Bounds.Height - 1);
+			return MapToCell(TileShape, CellToMap(TileShape, cell).Clamp(bounds));
 		}
 
 		public CPos ChooseRandomCell(MersenneTwister rand)
 		{
-			return new CPos(
-				rand.Next(Bounds.Left, Bounds.Right),
-				rand.Next(Bounds.Top, Bounds.Bottom));
+			var x = rand.Next(Bounds.Left, Bounds.Right);
+			var y = rand.Next(Bounds.Top, Bounds.Bottom);
+
+			return MapToCell(TileShape, new CPos(x, y));
 		}
 
 		public CPos ChooseRandomEdgeCell(MersenneTwister rand)
@@ -615,15 +685,16 @@ namespace OpenRA
 			var isX = rand.Next(2) == 0;
 			var edge = rand.Next(2) == 0;
 
-			return new CPos(
-				isX ? rand.Next(Bounds.Left, Bounds.Right) : (edge ? Bounds.Left : Bounds.Right),
-				!isX ? rand.Next(Bounds.Top, Bounds.Bottom) : (edge ? Bounds.Top : Bounds.Bottom));
+			var x = isX ? rand.Next(Bounds.Left, Bounds.Right) : (edge ? Bounds.Left : Bounds.Right);
+			var y = !isX ? rand.Next(Bounds.Top, Bounds.Bottom) :  (edge ? Bounds.Top : Bounds.Bottom);
+
+			return MapToCell(TileShape, new CPos(x, y));
 		}
 
 		public WRange DistanceToEdge(WPos pos, WVec dir)
 		{
-			var tl = CenterOfCell(new CPos(Bounds.Left, Bounds.Top)) - new WVec(512, 512, 0);
-			var br = CenterOfCell(new CPos(Bounds.Right, Bounds.Bottom)) + new WVec(511, 511, 0);
+			var tl = CenterOfCell(Cells.TopLeft) - new WVec(512, 512, 0);
+			var br = CenterOfCell(Cells.BottomRight) + new WVec(511, 511, 0);
 			var x = dir.X == 0 ? int.MaxValue : ((dir.X < 0 ? tl.X : br.X) - pos.X) / dir.X;
 			var y = dir.Y == 0 ? int.MaxValue : ((dir.Y < 0 ? tl.Y : br.Y) - pos.Y) / dir.Y;
 			return new WRange(Math.Min(x, y) * dir.Length);
diff --git a/OpenRA.Game/Widgets/MapPreviewWidget.cs b/OpenRA.Game/Widgets/MapPreviewWidget.cs
index 384bd8b316..c70aab3c0f 100644
--- a/OpenRA.Game/Widgets/MapPreviewWidget.cs
+++ b/OpenRA.Game/Widgets/MapPreviewWidget.cs
@@ -129,9 +129,10 @@ namespace OpenRA.Widgets
 				tooltipContainer.Value.RemoveTooltip();
 		}
 
-		public int2 ConvertToPreview(CPos point)
+		public int2 ConvertToPreview(CPos cell)
 		{
 			var preview = Preview();
+			var point = Map.CellToMap(preview.Map.TileShape, cell);
 			var dx = (int)(previewScale * (point.X - preview.Bounds.Left));
 			var dy = (int)(previewScale * (point.Y - preview.Bounds.Top));
 			return new int2(mapRect.X + dx, mapRect.Y + dy);
diff --git a/OpenRA.Mods.RA/Move/PathSearch.cs b/OpenRA.Mods.RA/Move/PathSearch.cs
index 1b61a86814..93a3ccb2fb 100755
--- a/OpenRA.Mods.RA/Move/PathSearch.cs
+++ b/OpenRA.Mods.RA/Move/PathSearch.cs
@@ -287,7 +287,7 @@ namespace OpenRA.Mods.RA.Move
 			while (CellInfoPool.Count > 0)
 			{
 				var cellInfo = GetFromPool();
-				if (cellInfo.Size != mapSize)
+				if (cellInfo.Size != mapSize || cellInfo.Shape != self.World.Map.TileShape)
 				{
 					Log.Write("debug", "Discarding old pooled CellInfo of wrong size.");
 					continue;
diff --git a/OpenRA.Mods.RA/Widgets/RadarWidget.cs b/OpenRA.Mods.RA/Widgets/RadarWidget.cs
index 960e484b5e..e7b4fdaa96 100755
--- a/OpenRA.Mods.RA/Widgets/RadarWidget.cs
+++ b/OpenRA.Mods.RA/Widgets/RadarWidget.cs
@@ -115,7 +115,7 @@ namespace OpenRA.Mods.RA.Widgets
 			var cell = MinimapPixelToCell(mi.Location);
 			var pos = world.Map.CenterOfCell(cell);
 			if ((mi.Event == MouseInputEvent.Down || mi.Event == MouseInputEvent.Move) && mi.Button == MouseButton.Left)
-				worldRenderer.Viewport.Center(world.Map.CenterOfCell(cell));
+				worldRenderer.Viewport.Center(pos);
 
 			if (mi.Event == MouseInputEvent.Down && mi.Button == MouseButton.Right)
 			{
@@ -242,8 +242,8 @@ namespace OpenRA.Mods.RA.Widgets
 
 		int2 CellToMinimapPixel(CPos p)
 		{
-			var mapOrigin = new CPos(world.Map.Bounds.Left, world.Map.Bounds.Top);
-			var mapOffset = p - mapOrigin;
+			var mapOrigin = new CVec(world.Map.Bounds.Left, world.Map.Bounds.Top);
+			var mapOffset = Map.CellToMap(world.Map.TileShape, p) - mapOrigin;
 
 			return new int2(mapRect.X, mapRect.Y) + (previewScale * new float2(mapOffset.X, mapOffset.Y)).ToInt2();
 		}
@@ -253,7 +253,7 @@ namespace OpenRA.Mods.RA.Widgets
 			var viewOrigin = new float2(mapRect.X, mapRect.Y);
 			var mapOrigin = new float2(world.Map.Bounds.Left, world.Map.Bounds.Top);
 			var fcell = mapOrigin + (1f / previewScale) * (p - viewOrigin);
-			return new CPos((int)fcell.X, (int)fcell.Y);
+			return Map.MapToCell(world.Map.TileShape, new CPos((int)fcell.X, (int)fcell.Y));
 		}
 	}
 }
diff --git a/OpenRA.Utility/LegacyMapImporter.cs b/OpenRA.Utility/LegacyMapImporter.cs
index ded0b9d2ab..ce83937535 100644
--- a/OpenRA.Utility/LegacyMapImporter.cs
+++ b/OpenRA.Utility/LegacyMapImporter.cs
@@ -149,8 +149,8 @@ namespace OpenRA.Utility
 
 			map.Smudges = Exts.Lazy(() => new List<SmudgeReference>());
 			map.Actors = Exts.Lazy(() => new Dictionary<string, ActorReference>());
-			map.MapResources = Exts.Lazy(() => new CellLayer<ResourceTile>(size));
-			map.MapTiles = Exts.Lazy(() => new CellLayer<TerrainTile>(size));
+			map.MapResources = Exts.Lazy(() => new CellLayer<ResourceTile>(TileShape.Rectangle, size));
+			map.MapTiles = Exts.Lazy(() => new CellLayer<TerrainTile>(TileShape.Rectangle, size));
 
 			map.Options = new MapOptions();