diff --git a/Substrate/SubstrateCS/Source/Chunk.cs b/Substrate/SubstrateCS/Source/Chunk.cs
index 79e2b68..6bfaa49 100644
--- a/Substrate/SubstrateCS/Source/Chunk.cs
+++ b/Substrate/SubstrateCS/Source/Chunk.cs
@@ -20,10 +20,10 @@ namespace Substrate
                 new NBTArrayNode("HeightMap", 256),
                 new NBTListNode("Entities", TagType.TAG_COMPOUND),
                 new NBTListNode("TileEntities", TagType.TAG_COMPOUND, TileEntity.BaseSchema),
-                //new NBTScalerNode("LastUpdate", TagType.TAG_LONG),
+                new NBTScalerNode("LastUpdate", TagType.TAG_LONG, NBTOptions.CREATE_ON_MISSING),
                 new NBTScalerNode("xPos", TagType.TAG_INT),
                 new NBTScalerNode("zPos", TagType.TAG_INT),
-                new NBTScalerNode("TerrainPopulated", TagType.TAG_BYTE),
+                new NBTScalerNode("TerrainPopulated", TagType.TAG_BYTE, NBTOptions.CREATE_ON_MISSING),
             },
         };
 
diff --git a/Substrate/SubstrateCS/Source/Level.cs b/Substrate/SubstrateCS/Source/Level.cs
index 4d8f7da..f6a5fc8 100644
--- a/Substrate/SubstrateCS/Source/Level.cs
+++ b/Substrate/SubstrateCS/Source/Level.cs
@@ -10,9 +10,24 @@ namespace Substrate
 
     public class Level : INBTObject<Level>, ICopyable<Level>
     {
-        public static NBTCompoundNode LevelSchema;
+        public static NBTCompoundNode LevelSchema = new NBTCompoundNode()
+        {
+            new NBTCompoundNode("Data")
+            {
+                new NBTScalerNode("Time", TagType.TAG_LONG),
+                new NBTScalerNode("LastPlayed", TagType.TAG_LONG),
+                new NBTCompoundNode("Player", Player.PlayerSchema, NBTOptions.OPTIONAL),
+                new NBTScalerNode("SpawnX", TagType.TAG_INT),
+                new NBTScalerNode("SpawnY", TagType.TAG_INT),
+                new NBTScalerNode("SpawnZ", TagType.TAG_INT),
+                new NBTScalerNode("SizeOnDisk", TagType.TAG_LONG),
+                new NBTScalerNode("RandomSeed", TagType.TAG_LONG),
+                new NBTScalerNode("version", TagType.TAG_INT, NBTOptions.OPTIONAL),
+                new NBTScalerNode("LevelName", TagType.TAG_STRING, NBTOptions.OPTIONAL),
+            },
+        };
 
-        private World _world;
+        private INBTWorld _world;
 
         private long _time;
         private long _lastPlayed;
@@ -42,7 +57,11 @@ namespace Substrate
         public Player Player
         {
             get { return _player; }
-            set { _player = value; }
+            set
+            {
+                _player = value;
+                _player.World = _name;
+            }
         }
 
         public int SpawnX
@@ -82,29 +101,29 @@ namespace Substrate
         public string LevelName
         {
             get { return _name; }
-            set { _name = value; }
+            set
+            {
+                _name = value;
+                if (_player != null) {
+                    _player.World = value;
+                }
+            }
         }
 
-        public Level (World world)
+        public Level (INBTWorld world)
         {
             _world = world;
 
-            LevelSchema = new NBTCompoundNode()
-            {
-                new NBTCompoundNode("Data")
-                {
-                    new NBTScalerNode("Time", TagType.TAG_LONG),
-                    new NBTScalerNode("LastPlayed", TagType.TAG_LONG),
-                    new NBTCompoundNode("Player", Player.PlayerSchema, NBTOptions.OPTIONAL),
-                    new NBTScalerNode("SpawnX", TagType.TAG_INT),
-                    new NBTScalerNode("SpawnY", TagType.TAG_INT),
-                    new NBTScalerNode("SpawnZ", TagType.TAG_INT),
-                    new NBTScalerNode("SizeOnDisk", TagType.TAG_LONG),
-                    new NBTScalerNode("RandomSeed", TagType.TAG_LONG),
-                    new NBTScalerNode("version", TagType.TAG_INT, NBTOptions.OPTIONAL),
-                    new NBTScalerNode("LevelName", TagType.TAG_STRING, NBTOptions.OPTIONAL),
-                },
-            };
+            // Sane defaults
+            _time = 0;
+            _lastPlayed = 0;
+            _spawnX = 0;
+            _spawnY = 64;
+            _spawnZ = 0;
+            _sizeOnDisk = 0;
+            _randomSeed = new Random().Next();
+            _version = 19132;
+            _name = "Untitled";
         }
 
         public Level (Level p)
@@ -126,6 +145,12 @@ namespace Substrate
             }
         }
 
+        public void SetDefaultPlayer ()
+        {
+            _player = new Player();
+            _player.World = _name;
+        }
+
         public bool Save ()
         {
             if (_world == null) {
diff --git a/Substrate/SubstrateCS/Source/Player.cs b/Substrate/SubstrateCS/Source/Player.cs
index 08a4861..ebb8e5d 100644
--- a/Substrate/SubstrateCS/Source/Player.cs
+++ b/Substrate/SubstrateCS/Source/Player.cs
@@ -80,6 +80,11 @@ namespace Substrate
             : base()
         {
             _inventory = new ItemCollection(_CAPACITY);
+
+            // Sane defaults
+            _dimension = 0;
+            _sleeping = 0;
+            _sleepTimer = 0;
         }
 
         public Player (Player p)
diff --git a/Substrate/SubstrateCS/Source/RegionManager.cs b/Substrate/SubstrateCS/Source/RegionManager.cs
index 8371c05..e84f14c 100644
--- a/Substrate/SubstrateCS/Source/RegionManager.cs
+++ b/Substrate/SubstrateCS/Source/RegionManager.cs
@@ -108,6 +108,16 @@ namespace Substrate
             return true;
         }
 
+        public int Save ()
+        {
+            int saved = 0;
+            foreach (Region r in _cache.Values) {
+                saved += r.Save();
+            }
+
+            return saved;
+        }
+
 
         #region IEnumerable<Region> Members
 
diff --git a/Substrate/SubstrateCS/Source/World.cs b/Substrate/SubstrateCS/Source/World.cs
index 4545972..1683c25 100644
--- a/Substrate/SubstrateCS/Source/World.cs
+++ b/Substrate/SubstrateCS/Source/World.cs
@@ -7,58 +7,149 @@ namespace Substrate
 {
     using NBT;
 
-    public abstract class World
+    public static class Dimension 
     {
-        private string _worldPath;
-
-        public string WorldPath
-        {
-            get { return _worldPath; }
-        }
-
-        protected World (string path)
-        {
-            _worldPath = path;
-
-            if (!File.Exists(Path.Combine(WorldPath, "level.dat"))) {
-                throw new Exception("Could not locate level.dat");
-            }
-        }
+        public const int NETHER = -1;
+        public const int DEFAULT = 0;
     }
 
-    public abstract class NBTWorld : World
+    public interface INBTWorld
     {
-        private Level _level;
-        private PlayerManager _playerMan;
+        string WorldPath { get; }
 
-        public Level Level
+        IBlockManager GetBlockManager ();
+        IBlockManager GetBlockManager (int dim);
+
+        IChunkManager GetChunkManager ();
+        IChunkManager GetChunkManager (int dim);
+    }
+
+    public class AlphaWorld : INBTWorld
+    {
+        protected string _path;
+        protected string _levelFile = "level.dat";
+
+        protected Level _level;
+
+        private Dictionary<int, ChunkFileManager> _chunkMgrs;
+        private Dictionary<int, BlockManager> _blockMgrs;
+
+        private AlphaWorld ()
         {
-            get { return _level; }
+            _chunkMgrs = new Dictionary<int, ChunkFileManager>();
+            _blockMgrs = new Dictionary<int, BlockManager>();
         }
 
-        public PlayerManager PlayerManager
+        public BlockManager GetBlockManager ()
         {
-            get { return _playerMan; }
+            return GetBlockManager(Dimension.DEFAULT);
         }
 
-        public abstract IChunkManager ChunkManager { get; }
-        public abstract IBlockManager BlockManager { get; }
-
-        protected NBTWorld (string path) 
-            : base(path)
+        public BlockManager GetBlockManager (int dim)
         {
+            BlockManager rm;
+            if (_blockMgrs.TryGetValue(dim, out rm)) {
+                return rm;
+            }
+
+            OpenDimension(dim);
+            return _blockMgrs[dim];
+        }
+
+        public ChunkFileManager GetChunkManager ()
+        {
+            return GetChunkManager(Dimension.DEFAULT);
+        }
+
+        public ChunkFileManager GetChunkManager (int dim)
+        {
+            ChunkFileManager rm;
+            if (_chunkMgrs.TryGetValue(dim, out rm)) {
+                return rm;
+            }
+
+            OpenDimension(dim);
+            return _chunkMgrs[dim];
+        }
+
+        public static AlphaWorld Open (string path)
+        {
+            return new AlphaWorld().OpenWorld(path) as AlphaWorld;
+        }
+
+        public static AlphaWorld Create (string path)
+        {
+            return new AlphaWorld().CreateWorld(path) as AlphaWorld;
+        }
+
+        public void Save ()
+        {
+            _level.Save();
+
+            foreach (KeyValuePair<int, ChunkFileManager> cm in _chunkMgrs) {
+                cm.Value.Save();
+            }
+        }
+
+        private void OpenDimension (int dim)
+        {
+            string path = _path;
+            if (dim != Dimension.DEFAULT) {
+                path = Path.Combine(path, "DIM" + dim);
+            }
+
+            if (!Directory.Exists(path)) {
+                Directory.CreateDirectory(path);
+            }
+
+            ChunkFileManager cm = new ChunkFileManager(path);
+            BlockManager bm = new BlockManager(cm);
+
+            _chunkMgrs[dim] = cm;
+            _blockMgrs[dim] = bm;
+        }
+
+        private AlphaWorld OpenWorld (string path)
+        {
+            if (!Directory.Exists(path)) {
+                if (File.Exists(path)) {
+                    _levelFile = Path.GetFileName(path);
+                    path = Path.GetDirectoryName(path);
+                }
+                else {
+                    throw new DirectoryNotFoundException("Directory '" + path + "' not found");
+                }
+            }
+
+            _path = path;
+
+            string ldat = Path.Combine(path, _levelFile);
+            if (!File.Exists(ldat)) {
+                throw new FileNotFoundException("Data file '" + _levelFile + "' not found in '" + path + "'", ldat);
+            }
+
             if (!LoadLevel()) {
-                throw new Exception("Failed to load level.dat");
+                throw new Exception("Failed to load '" + _levelFile + "'");
             }
 
-            if (Directory.Exists(Path.Combine(path, "players"))) {
-                _playerMan = new PlayerManager(Path.Combine(path, "players"));
-            }
+            return this;
         }
 
-        protected bool LoadLevel ()
+        private AlphaWorld CreateWorld (string path)
         {
-            NBTFile nf = new NBTFile(Path.Combine(WorldPath, "level.dat"));
+            if (!Directory.Exists(path)) {
+                throw new DirectoryNotFoundException("Directory '" + path + "' not found");
+            }
+
+            _path = path;
+            _level = new Level(this);
+
+            return this;
+        }
+
+        private bool LoadLevel ()
+        {
+            NBTFile nf = new NBTFile(Path.Combine(_path, _levelFile));
             Stream nbtstr = nf.GetDataInputStream();
             if (nbtstr == null) {
                 return false;
@@ -71,100 +162,231 @@ namespace Substrate
 
             return _level != null;
         }
+
+
+        #region INBTWorld Members
+
+        public string WorldPath
+        {
+            get { return _path; }
+        }
+
+        IBlockManager INBTWorld.GetBlockManager ()
+        {
+            return GetBlockManager();
+        }
+
+        IBlockManager INBTWorld.GetBlockManager (int dim)
+        {
+            return GetBlockManager(dim);
+        }
+
+        IChunkManager INBTWorld.GetChunkManager ()
+        {
+            return GetChunkManager();
+        }
+
+        IChunkManager INBTWorld.GetChunkManager (int dim)
+        {
+            return GetChunkManager(dim);
+        }
+
+        #endregion
     }
 
-    public class AlphaWorld : NBTWorld
-    {
-        private ChunkFileManager _chunkMan;
-        private BlockManager _blockMan;
+    public class BetaWorld : INBTWorld {
+        private const string _REGION_DIR = "region";
+        protected string _path;
+        protected string _levelFile = "level.dat";
 
-        private string _dim;
+        protected Level _level;
 
-        public AlphaWorld (string path)
-            : base(path)
+        private Dictionary<int, RegionManager> _regionMgrs;
+        private Dictionary<int, ChunkManager> _chunkMgrs;
+        private Dictionary<int, BlockManager> _blockMgrs;
+
+        private BetaWorld ()
         {
-            _chunkMan = new ChunkFileManager(path);
-            _blockMan = new BlockManager(_chunkMan);
+            _regionMgrs = new Dictionary<int, RegionManager>();
+            _chunkMgrs = new Dictionary<int, ChunkManager>();
+            _blockMgrs = new Dictionary<int, BlockManager>();
         }
 
-        public AlphaWorld (string path, string dim)
-            : base(path)
+        public BlockManager GetBlockManager ()
         {
-            _dim = dim;
-            if (_dim.Length > 0) {
-                path = Path.Combine(path, dim);
+            return GetBlockManager(Dimension.DEFAULT);
+        }
+
+        public BlockManager GetBlockManager (int dim)
+        {
+            BlockManager rm;
+            if (_blockMgrs.TryGetValue(dim, out rm)) {
+                return rm;
             }
 
-            _chunkMan = new ChunkFileManager(path);
-            _blockMan = new BlockManager(_chunkMan);
+            OpenDimension(dim);
+            return _blockMgrs[dim];
         }
 
-        public override IChunkManager ChunkManager
+        public ChunkManager GetChunkManager ()
         {
-            get { return _chunkMan; }
+            return GetChunkManager(Dimension.DEFAULT);
         }
 
-        public override IBlockManager BlockManager
+        public ChunkManager GetChunkManager (int dim)
         {
-            get { return _blockMan; }
+            ChunkManager rm;
+            if (_chunkMgrs.TryGetValue(dim, out rm)) {
+                return rm;
+            }
+
+            OpenDimension(dim);
+            return _chunkMgrs[dim];
         }
+
+        public RegionManager GetRegionManager ()
+        {
+            return GetRegionManager(Dimension.DEFAULT);
+        }
+
+        public RegionManager GetRegionManager (int dim)
+        {
+            RegionManager rm;
+            if (_regionMgrs.TryGetValue(dim, out rm)) {
+                return rm;
+            }
+
+            OpenDimension(dim);
+            return _regionMgrs[dim];
+        }
+
+        public static BetaWorld Open (string path)
+        {
+            return new BetaWorld().OpenWorld(path) as BetaWorld;
+        }
+
+        public static BetaWorld Create (string path)
+        {
+            return new BetaWorld().CreateWorld(path) as BetaWorld;
+        }
+
+        public void Save ()
+        {
+            _level.Save();
+
+            foreach (KeyValuePair<int, RegionManager> rm in _regionMgrs) {
+                rm.Value.Save();
+            }
+        }
+
+        private void OpenDimension (int dim)
+        {
+            string path = _path;
+            if (dim == Dimension.DEFAULT) {
+                path = Path.Combine(path, _REGION_DIR);
+            }
+            else {
+                path = Path.Combine(path, "DIM" + dim);
+                path = Path.Combine(path, _REGION_DIR);
+            }
+
+            if (!Directory.Exists(path)) {
+                Directory.CreateDirectory(path);
+            }
+
+            RegionManager rm = new RegionManager(path);
+            ChunkManager cm = new ChunkManager(rm);
+            BlockManager bm = new BlockManager(cm);
+
+            _regionMgrs[dim] = rm;
+            _chunkMgrs[dim] = cm;
+            _blockMgrs[dim] = bm;
+        }
+
+        private BetaWorld OpenWorld (string path)
+        {
+            if (!Directory.Exists(path)) {
+                if (File.Exists(path)) {
+                    _levelFile = Path.GetFileName(path);
+                    path = Path.GetDirectoryName(path);
+                }
+                else {
+                    throw new DirectoryNotFoundException("Directory '" + path + "' not found");
+                }
+            }
+
+            _path = path;
+
+            string ldat = Path.Combine(path, _levelFile);
+            if (!File.Exists(ldat)) {
+                throw new FileNotFoundException("Data file '" + _levelFile + "' not found in '" + path + "'", ldat);
+            }
+
+            if (!LoadLevel()) {
+                throw new Exception("Failed to load '" + _levelFile + "'");
+            }
+
+            return this;
+        }
+
+        private BetaWorld CreateWorld (string path)
+        {
+            if (!Directory.Exists(path)) {
+                throw new DirectoryNotFoundException("Directory '" + path + "' not found");
+            }
+
+            _path = path;
+            _level = new Level(this);
+
+            return this;
+        }
+
+        private bool LoadLevel ()
+        {
+            NBTFile nf = new NBTFile(Path.Combine(_path, _levelFile));
+            Stream nbtstr = nf.GetDataInputStream();
+            if (nbtstr == null) {
+                return false;
+            }
+
+            NBT_Tree tree = new NBT_Tree(nbtstr);
+
+            _level = new Level(this);
+            _level = _level.LoadTreeSafe(tree.Root);
+
+            return _level != null;
+        }
+
+
+        #region INBTWorld Members
+
+        public string WorldPath
+        {
+            get { return _path; }
+        }
+
+        IBlockManager INBTWorld.GetBlockManager ()
+        {
+            return GetBlockManager();
+        }
+
+        IBlockManager INBTWorld.GetBlockManager (int dim)
+        {
+            return GetBlockManager(dim);
+        }
+
+        IChunkManager INBTWorld.GetChunkManager ()
+        {
+            return GetChunkManager();
+        }
+
+        IChunkManager INBTWorld.GetChunkManager (int dim)
+        {
+            return GetChunkManager(dim);
+        }
+
+        #endregion
     }
 
-    public class BetaWorld : NBTWorld
-    {
-        private RegionManager _regionMan;
-        private ChunkManager _chunkMan;
-        private BlockManager _blockMan;
-
-        private string _dim;
-        private string _regionDir;
-
-        public RegionManager RegionManager
-        {
-            get { return _regionMan; }
-        }
-
-        public BetaWorld (string path)
-            : this(path, "region", "")
-        {
-        }
-
-        public BetaWorld (string path, string region)
-            : this(path, region, "")
-        {
-        }
-
-        public BetaWorld (string path, string region, string dim)
-            : base(path)
-        {
-            _regionDir = region;
-
-            _dim = dim;
-            if (_dim.Length > 0) {
-                path = Path.Combine(path, dim);
-            }
-
-            if (!Directory.Exists(Path.Combine(path, _regionDir))) {
-                throw new Exception("Could not find region directory");
-            }
-
-            _regionMan = new RegionManager(Path.Combine(path, _regionDir));
-            _chunkMan = new ChunkManager(_regionMan);
-            _blockMan = new BlockManager(_chunkMan);
-        }
-
-        public override IChunkManager ChunkManager
-        {
-            get { return _chunkMan; }
-        }
-
-        public override IBlockManager BlockManager
-        {
-            get { return _blockMan; }
-        }
-
-        //public static BetaWorld Open (string path);
-        //public static BetaWorld Create (string path);
-    }
-
+    public class DimensionNotFoundException : Exception { }
 }