diff --git a/ClassicalSharp/2D/IsometricBlockDrawer.cs b/ClassicalSharp/2D/IsometricBlockDrawer.cs
index f8a710716..c7f2c652c 100644
--- a/ClassicalSharp/2D/IsometricBlockDrawer.cs
+++ b/ClassicalSharp/2D/IsometricBlockDrawer.cs
@@ -38,11 +38,12 @@ namespace ClassicalSharp {
 			if( info.IsSprite[block] ) {
 				minBB = Vector3.Zero; maxBB = Vector3.One;
 			}
+			if( info.IsAir[block] ) return;
 			index = 0;
+			
 			// isometric coords size: cosY * -scale - sinY * scale
 			// we need to divide by (2 * cosY), as the calling function expects size to be in pixels.
-			scale = size / (2 * cosY);
-			
+			scale = size / (2 * cosY);		
 			// screen to isometric coords (cos(-x) = cos(x), sin(-x) = -sin(x))
 			pos.X = x; pos.Y = y; pos.Z = 0;			
 			pos = Utils.RotateY( Utils.RotateX( pos, cosX, -sinX ), cosY, -sinY );
diff --git a/ClassicalSharp/2D/Screens/ChatScreen.cs b/ClassicalSharp/2D/Screens/ChatScreen.cs
index cf02985e7..4fdfe78df 100644
--- a/ClassicalSharp/2D/Screens/ChatScreen.cs
+++ b/ClassicalSharp/2D/Screens/ChatScreen.cs
@@ -270,7 +270,7 @@ namespace ClassicalSharp {
 				} else {
 					textInput.HandlesKeyDown( key );
 				}
-				return true;
+				return key < Key.F1 || key > Key.F35;
 			}
 
 			if( key == game.Mapping( KeyBinding.OpenChat ) ) {
diff --git a/ClassicalSharp/Blocks/BlockInfo.Culling.cs b/ClassicalSharp/Blocks/BlockInfo.Culling.cs
index b499dca5e..319ea1f2e 100644
--- a/ClassicalSharp/Blocks/BlockInfo.Culling.cs
+++ b/ClassicalSharp/Blocks/BlockInfo.Culling.cs
@@ -9,6 +9,8 @@ namespace ClassicalSharp {
 		bool[] hidden = new bool[BlocksCount * BlocksCount * TileSide.Sides];
 		
 		public bool[] CanStretch = new bool[BlocksCount * TileSide.Sides];
+		
+		public bool[] IsAir = new bool[BlocksCount];
 
 		internal void CheckOpaque() {
 			for( int tile = 1; tile < BlocksCount; tile++ ) {
@@ -20,6 +22,7 @@ namespace ClassicalSharp {
 		}
 		
 		internal void SetupCullingCache() {
+			IsAir[0] = true;
 			CheckOpaque();
 			for( int i = 0; i < CanStretch.Length; i++ )
 				CanStretch[i] = true;
diff --git a/ClassicalSharp/Blocks/BlockInfo.cs b/ClassicalSharp/Blocks/BlockInfo.cs
index 7509d67f0..a5a616759 100644
--- a/ClassicalSharp/Blocks/BlockInfo.cs
+++ b/ClassicalSharp/Blocks/BlockInfo.cs
@@ -172,6 +172,7 @@ namespace ClassicalSharp {
 			BlocksLight[id] = true;
 			FullBright[id] = false;
 			CullWithNeighbours[id] = true;
+			IsAir[id] = false;
 			
 			Name[id] = "Invalid";
 			FogColour[id] = default( FastColour );
diff --git a/ClassicalSharp/Game/Game.cs b/ClassicalSharp/Game/Game.cs
index 06a8dbdc4..f75243461 100644
--- a/ClassicalSharp/Game/Game.cs
+++ b/ClassicalSharp/Game/Game.cs
@@ -441,7 +441,8 @@ namespace ClassicalSharp {
 		}
 		
 		internal bool CanPick( byte block ) {
-			if( block == 0 ) return false;
+			if( BlockInfo.CollideType[block] == BlockCollideType.WalkThrough ) 
+				return false;
 			if( !BlockInfo.IsLiquid[block] ) return true;
 			
 			return !LiquidsBreakable ? false :
diff --git a/ClassicalSharp/Map/ChunkMeshBuilder.cs b/ClassicalSharp/Map/ChunkMeshBuilder.cs
index 0808df556..2e8d19386 100644
--- a/ClassicalSharp/Map/ChunkMeshBuilder.cs
+++ b/ClassicalSharp/Map/ChunkMeshBuilder.cs
@@ -48,7 +48,7 @@ namespace ClassicalSharp {
 					int chunkIndex = (yy + 1) * extChunkSize2 + (zz + 1) * extChunkSize + (0 + 1);
 					for( int x = x1, xx = 0; x < xMax; x++, xx++ ) {						
 						tile = chunk[chunkIndex];
-						if( tile != 0 )
+						if( !info.IsAir[tile] )
 							RenderTile( chunkIndex, xx, yy, zz, x, y, z );
 						chunkIndex++;
 					}
@@ -59,12 +59,8 @@ namespace ClassicalSharp {
 		
 		unsafe bool ReadChunkData( int x1, int y1, int z1 ) {
 			bool allAir = true, allSolid = true;
-			fixed( byte* chunkPtr = chunk, mapPtr = map.mapData ) {
-				
-				int* chunkIntPtr = (int*)chunkPtr;
-				for( int i = 0; i < extChunkSize3 / sizeof( int ); i++ ) {
-					*chunkIntPtr++ = 0;
-				}
+			fixed( byte* chunkPtr = chunk, mapPtr = map.mapData ) {				
+				MemUtils.memset( (IntPtr)chunkPtr, 0, 0, extChunkSize3 );
 				
 				for( int yy = -1; yy < 17; yy++ ) {
 					int y = yy + y1;
@@ -75,8 +71,8 @@ namespace ClassicalSharp {
 						if( z < 0 ) continue;
 						if( z > maxZ ) break;
 						
-						int index = ( y * length + z ) * width + ( x1 - 1 - 1 );
-						int chunkIndex = ( yy + 1 ) * extChunkSize2 + ( zz + 1 ) * extChunkSize + ( -1 + 1 ) - 1;
+						int index = (y * length + z) * width + (x1 - 1 - 1);
+						int chunkIndex = (yy + 1) * extChunkSize2 + (zz + 1) * extChunkSize + (-1 + 1) - 1;
 						
 						for( int xx = -1; xx < 17; xx++ ) {
 							int x = xx + x1;
@@ -160,10 +156,9 @@ namespace ClassicalSharp {
 				DrawTopFace( topCount );
 		}
 		
-		void Stretch( int x1, int y1, int z1 ) {
-			for( int i = 0; i < counts.Length; i++ ) {
-				counts[i] = 1;
-			}
+		unsafe void Stretch( int x1, int y1, int z1 ) {
+			fixed( byte* ptr = counts )
+				MemUtils.memset( (IntPtr)ptr, 1, 0, chunkSize3 * TileSide.Sides );
 			
 			int xMax = Math.Min( width, x1 + chunkSize );
 			int yMax = Math.Min( height, y1 + chunkSize );
@@ -187,7 +182,7 @@ namespace ClassicalSharp {
 					for( int x = x1, xx = 0; x < xMax; x++, xx++ ) {
 						chunkIndex++;
 						byte tile = chunk[chunkIndex];
-						if( tile == 0 ) continue;
+						if( info.IsAir[tile] ) continue;
 						int countIndex = ((yy << 8) + (zz << 4) + xx) * TileSide.Sides;
 						
 						// Sprites only use one face to indicate stretching count, so we can take a shortcut here.
diff --git a/ClassicalSharp/Model/BlockModel.cs b/ClassicalSharp/Model/BlockModel.cs
index d70671944..c74baf184 100644
--- a/ClassicalSharp/Model/BlockModel.cs
+++ b/ClassicalSharp/Model/BlockModel.cs
@@ -42,7 +42,7 @@ namespace ClassicalSharp.Model {
 		}
 		
 		public void CalcState( byte block ) {
-			if( block == 0 ) {
+			if( game.BlockInfo.IsAir[block] ) {
 				bright = false;
 				minBB = Vector3.Zero;
 				maxBB = Vector3.One;
@@ -71,7 +71,7 @@ namespace ClassicalSharp.Model {
 			}
 			
 			CalcState( block );
-			if( block == 0 )
+			if( game.BlockInfo.IsAir[block] )
 				return;
 			lastTexId = -1;
 			atlas = game.TerrainAtlas1D;
diff --git a/ClassicalSharp/Network/NetworkProcessor.CPE.cs b/ClassicalSharp/Network/NetworkProcessor.CPE.cs
index 8d03079e9..4f3eb18cc 100644
--- a/ClassicalSharp/Network/NetworkProcessor.CPE.cs
+++ b/ClassicalSharp/Network/NetworkProcessor.CPE.cs
@@ -460,6 +460,9 @@ namespace ClassicalSharp {
 				info.CullWithNeighbours[block] = false;
 			} else if( blockDraw == 3 ) {
 				info.IsTranslucent[block] = true;
+			} else if( blockDraw == 4 ) {
+				info.IsTransparent[block] = true;
+				info.IsAir[block] = true;
 			}
 			if( info.IsOpaque[block] )
 				info.IsOpaque[block] = blockDraw == 0;