Replay stuff.

FYI: Don't try to replay a game where you built any vehicles. It WILL fail horribly.

OpenRa.Game/Order.cs

@@ -2,7 +2,8 @@ using System;
 using System.Collections.Generic;
 using System.Text;
 using System.Linq;
-using OpenRa.Game.Traits;
+using OpenRa.Game.Traits;
+using System.IO;
 
 namespace OpenRa.Game
 {
@@ -23,10 +24,67 @@ namespace OpenRa.Game
 			this.TargetActor = targetActor;
 			this.TargetLocation = targetLocation;
 			this.TargetString = targetString;
-		}
-
-		// TODO: serialize / deserialize
-
+		}
+
+		public byte[] Serialize()
+		{
+			switch( OrderString )
+			{
+			// Format:
+			//		u32   : player, with msb set. (if msb is clear, not an order)
+			//		u8    : orderID.
+			//		            0xFF: Full serialized order.
+			//		varies: rest of order.
+			default:
+				// TODO: specific serializers for specific orders.
+				{
+					var ret = new MemoryStream();
+					var w = new BinaryWriter(ret);
+					w.Write( (uint)Player.Palette | 0x80000000u );
+					w.Write( (byte)0xFF ); // 
+					w.Write( OrderString );
+					w.Write( Subject == null ? 0xFFFFFFFF : Subject.ActorID );
+					w.Write( TargetActor == null ? 0xFFFFFFFF : TargetActor.ActorID );
+					w.Write( TargetLocation.X );
+					w.Write( TargetLocation.Y );
+					w.Write( TargetString != null );
+					if( TargetString != null )
+						w.Write( TargetString );
+					return ret.ToArray();
+				}
+			}
+		}
+
+		public static Order Deserialize( BinaryReader r, uint first )
+		{
+			if( ( first >> 31 ) == 0 ) return null;
+
+			var player = Game.players.Where( x => x.Value.Palette == (first & 0x7FFFFFFF) ).First().Value;
+			switch( r.ReadByte() )
+			{
+			case 0xFF:
+				{
+					var order = r.ReadString();
+					var subject = ActorFromUInt( r.ReadUInt32() );
+					var targetActor = ActorFromUInt( r.ReadUInt32() );
+					var targetLocation = new int2( r.ReadInt32(), 0 );
+					targetLocation.Y = r.ReadInt32();
+					var targetString = null as string;
+					if( r.ReadBoolean() )
+						targetString = r.ReadString();
+					return new Order( player, order, subject, targetActor, targetLocation, targetString );
+				}
+			default:
+				throw new NotImplementedException();
+			}
+		}
+
+		static Actor ActorFromUInt( uint aID )
+		{
+			if( aID == 0xFFFFFFFF ) return null;
+			return Game.world.Actors.Where( x => x.ActorID == aID ).First();
+		}
+
 		public static Order Attack( Actor subject, Actor target )
 		{
 			return new Order( subject.Owner, "Attack", subject, target, int2.Zero, null );
@@ -45,6 +103,6 @@ namespace OpenRa.Game
 		public static Order PlaceBuilding( Player subject, int2 target, string buildingName )
 		{
 			return new Order( subject, "PlaceBuilding", null, null, target, buildingName );
-		}
+		}
 	}
 }