diff --git a/84 Super Star Trek/csharp/Game.cs b/84 Super Star Trek/csharp/Game.cs
index d97b8198..eb9fe03c 100644
--- a/84 Super Star Trek/csharp/Game.cs	
+++ b/84 Super Star Trek/csharp/Game.cs	
@@ -33,11 +33,7 @@ namespace SuperStarTrek
         {
             _output.Write(Strings.Title);
 
-            _output.Write("Do you need instructions (Y/N)? ");
-            var response = Console.ReadLine();
-            _output.WriteLine();
-
-            if (!response.Equals("N", InvariantCultureIgnoreCase))
+            if (_input.GetYesNo("Do you need instructions", Input.YesNoMode.FalseOnN))
             {
                 _output.Write(Strings.Instructions);
 
@@ -68,7 +64,16 @@ namespace SuperStarTrek
             {
                 var command = _input.GetCommand();
 
-                gameOver = command == Command.XXX || _enterprise.Execute(command);
+                gameOver = command == Command.XXX || _enterprise.Execute(command) || CheckIfStranded();
+            }
+
+            if (_galaxy.KlingonCount > 0)
+            {
+                _output.Write(Strings.EndOfMission, _currentStardate, _galaxy.KlingonCount);
+            }
+            else
+            {
+                _output.Write(Strings.Congratulations, GetEfficiency());
             }
         }
 
@@ -86,12 +91,29 @@ namespace SuperStarTrek
             _initialKlingonCount = _galaxy.KlingonCount;
 
             _enterprise = new Enterprise(3000, random.GetCoordinate());
-            _enterprise.Add(new ShortRangeSensors(_enterprise, _galaxy, this, _output))
-                .Add(new ShieldControl(_enterprise, _output, _input));
+            _enterprise
+                .Add(new ShortRangeSensors(_enterprise, _galaxy, this, _output))
+                .Add(new ShieldControl(_enterprise, _output, _input))
+                .Add(new DamageControl(_enterprise, _output));
 
             return new Quadrant(_galaxy[_currentQuadrant], _enterprise);
         }
 
         public bool Replay() => _galaxy.StarbaseCount > 0 && _input.GetString(Strings.ReplayPrompt, "Aye");
+
+        private bool CheckIfStranded()
+        {
+            if (_enterprise.TotalEnergy < 10 ||
+                _enterprise.Energy < 10 && _enterprise.Shields.IsDamaged)
+            {
+                _output.Write(Strings.Stranded);
+                return true;
+            }
+
+            return false;
+        }
+
+        private double GetEfficiency() =>
+            1000 * Math.Pow(_initialKlingonCount / (_currentStardate - _initialStardate), 2);
     }
 }
diff --git a/84 Super Star Trek/csharp/Input.cs b/84 Super Star Trek/csharp/Input.cs
index 98e5b297..3e2d7972 100644
--- a/84 Super Star Trek/csharp/Input.cs	
+++ b/84 Super Star Trek/csharp/Input.cs	
@@ -72,5 +72,26 @@ namespace SuperStarTrek
                 _output.WriteLine();
             }
         }
+
+        public bool GetYesNo(string prompt, YesNoMode mode)
+        {
+            _output.Prompt($"{prompt} (Y/N)");
+            var response = Console.ReadLine().ToUpperInvariant();
+
+            return (mode, response) switch
+            {
+                (YesNoMode.FalseOnN, "N") => false,
+                (YesNoMode.FalseOnN, _) => true,
+                (YesNoMode.TrueOnY, "Y") => true,
+                (YesNoMode.TrueOnY, _) => false,
+                _ => throw new ArgumentOutOfRangeException(nameof(mode), mode, "Invalid value")
+            };
+        }
+
+        public enum YesNoMode
+        {
+            TrueOnY,
+            FalseOnN
+        }
     }
 }
diff --git a/84 Super Star Trek/csharp/Objects/Enterprise.cs b/84 Super Star Trek/csharp/Objects/Enterprise.cs
index 4f6055cc..e8447fca 100644
--- a/84 Super Star Trek/csharp/Objects/Enterprise.cs	
+++ b/84 Super Star Trek/csharp/Objects/Enterprise.cs	
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 using SuperStarTrek.Resources;
 using SuperStarTrek.Space;
@@ -13,7 +14,6 @@ namespace SuperStarTrek.Objects
         private readonly List<Subsystem> _systems;
         private readonly Dictionary<Command, Subsystem> _commandExecutors;
         private Quadrant _quadrant;
-        private ShieldControl _shieldControl;
 
         public Enterprise(int maxEnergy, Coordinates sector)
         {
@@ -27,11 +27,12 @@ namespace SuperStarTrek.Objects
         public Coordinates Quadrant => _quadrant.Coordinates;
         public Coordinates Sector { get; }
         public string Condition => GetCondition();
-        public double Shields => _shieldControl.Energy;
-        public double Energy => TotalEnergy - Shields;
+        public ShieldControl Shields => (ShieldControl)_commandExecutors[Command.SHE];
+        public double Energy => TotalEnergy - Shields.Energy;
         public double TotalEnergy { get; private set; }
+        public int DamagedSystemCount => _systems.Count(s => s.IsDamaged);
+        public IEnumerable<Subsystem> Systems => _systems;
         public int TorpedoCount { get; }
-
         public bool IsDocked { get; private set; }
 
         public Enterprise Add(Subsystem system)
@@ -39,23 +40,9 @@ namespace SuperStarTrek.Objects
             _systems.Add(system);
             _commandExecutors[system.Command] = system;
 
-            if (system is ShieldControl shieldControl) { _shieldControl = shieldControl; }
-
             return this;
         }
 
-        public string GetDamageReport()
-        {
-            var report = new StringBuilder();
-            report.AppendLine().AppendLine().AppendLine("Device             State of Repair");
-            foreach (var system in _systems)
-            {
-                report.Append(system.Name.PadRight(25)).AppendLine(system.Condition.ToString(" 0.00;-0.00"));
-            }
-            report.AppendLine();
-            return report.ToString();
-        }
-
         public void Enter(Quadrant quadrant, string entryTextFormat)
         {
             _quadrant = quadrant;
@@ -66,7 +53,7 @@ namespace SuperStarTrek.Objects
             if (quadrant.HasKlingons)
             {
                 _output.Write(Strings.CombatArea);
-                if (Shields <= 200) { _output.Write(Strings.LowShields); }
+                if (Shields.Energy <= 200) { _output.Write(Strings.LowShields); }
             }
 
             IsDocked = quadrant.EnterpriseIsNextToStarbase;
diff --git a/84 Super Star Trek/csharp/Objects/Starbase.cs b/84 Super Star Trek/csharp/Objects/Starbase.cs
index 33110837..e11ca9f5 100644
--- a/84 Super Star Trek/csharp/Objects/Starbase.cs	
+++ b/84 Super Star Trek/csharp/Objects/Starbase.cs	
@@ -1,7 +1,38 @@
+using SuperStarTrek.Resources;
+
 namespace SuperStarTrek.Objects
 {
     internal class Starbase
     {
+        private readonly Input _input;
+        private readonly Output _output;
+        private readonly double _repairDelay;
+
+        public Starbase(Random random, Input input)
+        {
+            _repairDelay = random.GetDouble() * 0.5;
+            _input = input;
+        }
+
         public override string ToString() => ">!<";
+
+        internal bool TryRepair(Enterprise enterprise, out double repairTime)
+        {
+            repairTime = enterprise.DamagedSystemCount * 0.1 + _repairDelay;
+            if (repairTime >= 1) { repairTime = 0.9; }
+
+            _output.Write(Strings.RepairEstimate, repairTime);
+            if (_input.GetYesNo(Strings.RepairPrompt, Input.YesNoMode.TrueOnY))
+            {
+                foreach (var system in enterprise.Systems)
+                {
+                    system.Repair();
+                }
+                return true;
+            }
+
+            repairTime = 0;
+            return false;
+        }
     }
 }
diff --git a/84 Super Star Trek/csharp/Output.cs b/84 Super Star Trek/csharp/Output.cs
index 77e5e919..ed960eea 100644
--- a/84 Super Star Trek/csharp/Output.cs	
+++ b/84 Super Star Trek/csharp/Output.cs	
@@ -4,12 +4,37 @@ namespace SuperStarTrek
 {
     internal class Output
     {
-        public void Write(string text) => Console.Write(text);
-        public void Write(string format, params object[] args) => Console.Write(format, args);
-        public void WriteLine(string text = "") => Console.WriteLine(text);
+        public Output Write(string text)
+        {
+            Console.Write(text);
+            return this;
+        }
 
-        public void NextLine() => Console.WriteLine();
+        public Output Write(string format, params object[] args)
+        {
+            Console.Write(format, args);
+            return this;
+        }
+
+        public Output WriteLine(string text = "")
+        {
+            Console.WriteLine(text);
+            return this;
+        }
+
+
+        public Output NextLine()
+        {
+            Console.WriteLine();
+            return this;
+        }
+
+
+        public Output Prompt(string text = "")
+        {
+            Console.Write($"{text}? ");
+            return this;
+        }
 
-        public void Prompt(string text = "") => Console.Write($"{text}? ");
     }
 }
diff --git a/84 Super Star Trek/csharp/Resources/AcceptCommand.txt b/84 Super Star Trek/csharp/Resources/AcceptCommand.txt
deleted file mode 100644
index e69de29b..00000000
diff --git a/84 Super Star Trek/csharp/Resources/Congratulations.txt b/84 Super Star Trek/csharp/Resources/Congratulations.txt
new file mode 100644
index 00000000..767f8653
--- /dev/null
+++ b/84 Super Star Trek/csharp/Resources/Congratulations.txt	
@@ -0,0 +1,4 @@
+Congratulations, Captain!  The last Klingon battle cruiser
+menacing the Federation has been destroyed.
+
+Your efficiency rating is {0}.
diff --git a/84 Super Star Trek/csharp/Resources/Destroyed.txt b/84 Super Star Trek/csharp/Resources/Destroyed.txt
new file mode 100644
index 00000000..881d7b49
--- /dev/null
+++ b/84 Super Star Trek/csharp/Resources/Destroyed.txt	
@@ -0,0 +1 @@
+The Enterprise has been destroyed.  The Federation will be conquered.
diff --git a/84 Super Star Trek/csharp/Resources/EndOfMission.txt b/84 Super Star Trek/csharp/Resources/EndOfMission.txt
new file mode 100644
index 00000000..f6995e31
--- /dev/null
+++ b/84 Super Star Trek/csharp/Resources/EndOfMission.txt	
@@ -0,0 +1,3 @@
+Is is stardate {0}.
+There were {1} Klingon battle cruisers left at
+the end of your mission.
diff --git a/84 Super Star Trek/csharp/Resources/Instructions.txt b/84 Super Star Trek/csharp/Resources/Instructions.txt
index fd74857e..34b4169c 100644
--- a/84 Super Star Trek/csharp/Resources/Instructions.txt	
+++ b/84 Super Star Trek/csharp/Resources/Instructions.txt	
@@ -1,3 +1,4 @@
+
       INSTRUCTIONS FOR 'SUPER STAR TREK'
 
 1. When you see "Command ?" printed, enter one of the legal
diff --git a/84 Super Star Trek/csharp/Resources/RepairEstimate.txt b/84 Super Star Trek/csharp/Resources/RepairEstimate.txt
new file mode 100644
index 00000000..12e167a5
--- /dev/null
+++ b/84 Super Star Trek/csharp/Resources/RepairEstimate.txt	
@@ -0,0 +1,2 @@
+Technicians standing by to effect repairs to your ship;
+Estimated time to repair: {0} stardates.
diff --git a/84 Super Star Trek/csharp/Resources/RepairPrompt.txt b/84 Super Star Trek/csharp/Resources/RepairPrompt.txt
new file mode 100644
index 00000000..feffdb27
--- /dev/null
+++ b/84 Super Star Trek/csharp/Resources/RepairPrompt.txt	
@@ -0,0 +1 @@
+Will you authorize the repair order (Y/N)
\ No newline at end of file
diff --git a/84 Super Star Trek/csharp/Resources/ReplayPrompt.txt b/84 Super Star Trek/csharp/Resources/ReplayPrompt.txt
index 52aca0d1..3ca3a102 100644
--- a/84 Super Star Trek/csharp/Resources/ReplayPrompt.txt	
+++ b/84 Super Star Trek/csharp/Resources/ReplayPrompt.txt	
@@ -1,3 +1,5 @@
+
+
 The Federation is in need of a new starship commander
 for a similar mission -- if there is a volunteer
 let him step forward and enter 'Aye'
\ No newline at end of file
diff --git a/84 Super Star Trek/csharp/Resources/Stranded.txt b/84 Super Star Trek/csharp/Resources/Stranded.txt
new file mode 100644
index 00000000..07c37952
--- /dev/null
+++ b/84 Super Star Trek/csharp/Resources/Stranded.txt	
@@ -0,0 +1,3 @@
+** FATAL ERROR **   You've just stranded your ship in space
+You have insufficient maneuvering energy, and shield control
+is presently incapable of cross-circuiting to engine room!!
diff --git a/84 Super Star Trek/csharp/Resources/Strings.cs b/84 Super Star Trek/csharp/Resources/Strings.cs
index 930f1663..4592db31 100644
--- a/84 Super Star Trek/csharp/Resources/Strings.cs	
+++ b/84 Super Star Trek/csharp/Resources/Strings.cs	
@@ -7,14 +7,20 @@ namespace SuperStarTrek.Resources
     internal static class Strings
     {
         public static string CombatArea => GetResource();
+        public static string Congratulations => GetResource();
+        public static string Destroyed => GetResource();
+        public static string EndOfMission => GetResource();
         public static string Enterprise => GetResource();
         public static string Instructions => GetResource();
         public static string LowShields => GetResource();
         public static string Orders => GetResource();
+        public static string RepairEstimate => GetResource();
+        public static string RepairPrompt => GetResource();
         public static string ReplayPrompt => GetResource();
         public static string ShieldsDropped => GetResource();
         public static string ShortRangeSensorsOut => GetResource();
         public static string StartText => GetResource();
+        public static string Stranded => GetResource();
         public static string Title => GetResource();
 
         private static string GetResource([CallerMemberName] string name = "")
diff --git a/84 Super Star Trek/csharp/Space/Quadrant.cs b/84 Super Star Trek/csharp/Space/Quadrant.cs
index 2aa45b6d..f08fa18b 100644
--- a/84 Super Star Trek/csharp/Space/Quadrant.cs	
+++ b/84 Super Star Trek/csharp/Space/Quadrant.cs	
@@ -23,7 +23,7 @@ namespace SuperStarTrek.Space
             PositionObject(() => new Klingon(), _info.KlingonCount);
             if (_info.HasStarbase)
             {
-                _starbaseSector = PositionObject(() => new Starbase());
+                _starbaseSector = PositionObject(() => new Starbase(_random, new Input(new Output())));
             }
             PositionObject(() => new Star(), _info.StarCount);
         }
@@ -31,6 +31,7 @@ namespace SuperStarTrek.Space
         public Coordinates Coordinates => _info.Coordinates;
         public bool HasKlingons => _info.KlingonCount > 0;
         public bool HasStarbase => _info.HasStarbase;
+        public Starbase Starbase => HasStarbase ? (Starbase)_sectors[_starbaseSector] : null;
         public bool EnterpriseIsNextToStarbase =>
             _info.HasStarbase &&
             Math.Abs(_enterpriseSector.X - _starbaseSector.X) <= 1 &&
diff --git a/84 Super Star Trek/csharp/Systems/DamageControl.cs b/84 Super Star Trek/csharp/Systems/DamageControl.cs
new file mode 100644
index 00000000..5cfbda7e
--- /dev/null
+++ b/84 Super Star Trek/csharp/Systems/DamageControl.cs	
@@ -0,0 +1,49 @@
+using SuperStarTrek.Objects;
+using SuperStarTrek.Space;
+
+namespace SuperStarTrek.Systems
+{
+    internal class DamageControl : Subsystem
+    {
+        private readonly Enterprise _enterprise;
+        private readonly Output _output;
+
+        public DamageControl(Enterprise enterprise, Output output)
+            : base("Damage Control", Command.DAM)
+        {
+            _enterprise = enterprise;
+            _output = output;
+        }
+
+        public override void ExecuteCommand(Quadrant quadrant)
+        {
+            if (IsDamaged)
+            {
+                _output.WriteLine("Damage Control report not available");
+            }
+            else
+            {
+                WriteDamageReport();
+            }
+
+            if (_enterprise.DamagedSystemCount > 0 && _enterprise.IsDocked)
+            {
+                if (quadrant.Starbase.TryRepair(_enterprise, out var repairTime))
+                {
+                    WriteDamageReport();
+                }
+            }
+        }
+
+        public void WriteDamageReport()
+        {
+            _output.NextLine().NextLine().WriteLine("Device             State of Repair");
+            foreach (var system in _enterprise.Systems)
+            {
+                _output.Write(system.Name.PadRight(25))
+                    .WriteLine(((int)(system.Condition * 100) * 0.01).ToString(" 0.##;-0.##"));
+            }
+            _output.NextLine();
+        }
+    }
+}
diff --git a/84 Super Star Trek/csharp/Systems/ShortRangeSensors.cs b/84 Super Star Trek/csharp/Systems/ShortRangeSensors.cs
index d22dda70..6632705c 100644
--- a/84 Super Star Trek/csharp/Systems/ShortRangeSensors.cs	
+++ b/84 Super Star Trek/csharp/Systems/ShortRangeSensors.cs	
@@ -51,8 +51,8 @@ namespace SuperStarTrek.Systems
             yield return $"Quadrant           {_enterprise.Quadrant}";
             yield return $"Sector             {_enterprise.Sector}";
             yield return $"Photon torpedoes   {_enterprise.TorpedoCount}";
-            yield return $"Total energy       {Math.Ceiling(_enterprise.Energy)}";
-            yield return $"Shields            {(int)_enterprise.Shields}";
+            yield return $"Total energy       {Math.Ceiling(_enterprise.TotalEnergy)}";
+            yield return $"Shields            {(int)_enterprise.Shields.Energy}";
             yield return $"Klingons remaining {_galaxy.KlingonCount}";
         }
     }
diff --git a/84 Super Star Trek/csharp/Systems/Subsystem.cs b/84 Super Star Trek/csharp/Systems/Subsystem.cs
index ae2ef7d6..9cb461ce 100644
--- a/84 Super Star Trek/csharp/Systems/Subsystem.cs	
+++ b/84 Super Star Trek/csharp/Systems/Subsystem.cs	
@@ -12,9 +12,14 @@ namespace SuperStarTrek.Systems
         }
 
         public string Name { get; }
-        public double Condition { get; }
+        public double Condition { get; private set; }
+        public bool IsDamaged => Condition < 0;
         public Command Command { get; }
 
         public abstract void ExecuteCommand(Quadrant quadrant);
+        public void Repair()
+        {
+            if (Condition < 0) { Condition = 0; }
+        }
     }
 }