diff --git a/projects/AstroBalance/Assets/Scripts/RocketLaunch/LaunchControl.cs b/projects/AstroBalance/Assets/Scripts/RocketLaunch/LaunchControl.cs
index a2f51b52..6e7ef37d 100644
--- a/projects/AstroBalance/Assets/Scripts/RocketLaunch/LaunchControl.cs
+++ b/projects/AstroBalance/Assets/Scripts/RocketLaunch/LaunchControl.cs
@@ -64,7 +64,7 @@ void Start()
         tracker = FindFirstObjectByType<Tracker>();
 
         SaveData<RocketLaunchData> saveData = new(saveFilename);
-        RocketLaunchData lastGameData = saveData.GetLastGameData();
+        RocketLaunchData lastGameData = saveData.GetLastCompleteGameData();
 
         if (lastGameData == null)
         {
diff --git a/projects/AstroBalance/Assets/Scripts/SaveData.cs b/projects/AstroBalance/Assets/Scripts/SaveData.cs
index d51c487f..39bbfeca 100644
--- a/projects/AstroBalance/Assets/Scripts/SaveData.cs
+++ b/projects/AstroBalance/Assets/Scripts/SaveData.cs
@@ -1,6 +1,9 @@
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Reflection;
+using System.Text;
 using UnityEngine;
 
 /// <summary>
@@ -9,22 +12,21 @@
 /// <typeparam name="T">The type of game data (specific to each mini-game)</typeparam>
 [System.Serializable]
 public class SaveData<T>
-    where T : GameData
+    where T : GameData, new()
 {
-    public List<T> savedGames = new List<T>();
+    private bool saveFileExists = false;
     private string dataPath;
 
     /// <summary>
     /// Create a new Save Data collection. If available, this will
-    /// be populated with previous save data from filename.json
+    /// build on previous save data from filename.csv
     /// </summary>
     /// <param name="filename">The filename of the save file</param>
     public SaveData(string filename)
     {
         // currently defaults to "C:\Users\username\AppData\LocalLow\DefaultCompany\AstroBalance" on Windows
-        dataPath = Path.Combine(Application.persistentDataPath, filename + ".json");
-
-        Load();
+        dataPath = Path.Combine(Application.persistentDataPath, filename + ".csv");
+        CheckSaveFileExists();
     }
 
     /// <summary>
@@ -33,47 +35,166 @@ public SaveData(string filename)
     /// <param name="gameData">Game data from this session</param>
     public void SaveGameData(T gameData)
     {
-        savedGames.Add(gameData);
-        Save();
+        using (StreamWriter sw = new StreamWriter(dataPath, true))
+        {
+            if (!saveFileExists)
+            {
+                sw.WriteLine(GameDataToCsv(gameData, true));
+                saveFileExists = true;
+            }
+
+            sw.WriteLine(GameDataToCsv(gameData, false));
+        }
     }
 
     /// <summary>
-    /// Get data from the last played game session.
+    /// Get data from the last complete played game session.
     /// </summary>
-    public T GetLastGameData()
+    public T GetLastCompleteGameData()
     {
-        return savedGames.LastOrDefault();
+        if (!saveFileExists)
+        {
+            return null;
+        }
+
+        IEnumerable<T> lastGameData = GetLastNCompleteGamesData(1);
+        if (lastGameData.Count() != 1)
+        {
+            return null;
+        }
+        else
+        {
+            return lastGameData.ElementAt(0);
+        }
     }
 
     /// <summary>
-    /// Get data from the last n played games.
+    /// Get data from the last n complete played games.
     /// </summary>
     /// <param name="nGames">Number of games to retrieve</param>
-    public IEnumerable<T> GetLastNGamesData(int nGames)
+    public IEnumerable<T> GetLastNCompleteGamesData(int nGames)
     {
-        return savedGames.TakeLast(nGames);
+        List<T> lastCompleteGames = new List<T>();
+        if (!saveFileExists)
+        {
+            return lastCompleteGames;
+        }
+
+        IEnumerable<string> csvLines = File.ReadLines(dataPath);
+        string header = csvLines.First();
+        int lineNo = csvLines.Count() - 1;
+
+        // Start from end of file, and find n complete games
+        while (lineNo > 0 && lastCompleteGames.Count() < nGames)
+        {
+            string line = File.ReadLines(dataPath).ElementAt(lineNo);
+
+            T gameData = CsvToGameData(header, line);
+            if (gameData.gameCompleted)
+            {
+                lastCompleteGames.Add(gameData);
+            }
+            lineNo--;
+        }
+
+        return lastCompleteGames;
     }
 
-    public void Save()
+    /// <summary>
+    /// Convert csv header / row into a GameData object.
+    /// </summary>
+    /// <param name="csvHeader">Csv header as string (first line of csv file)</param>
+    /// <param name="csvRow">Csv row as string</param>
+    /// <returns>GameData object with fields populated by row values</returns>
+    private T CsvToGameData(string csvHeader, string csvRow)
     {
-        string json = JsonUtility.ToJson(this, true);
-        File.WriteAllText(dataPath, json);
+        string[] headerNames = csvHeader.Split(',');
+        string[] values = csvRow.Split(",");
+
+        T gameData = new();
+        for (int i = 0; i < headerNames.Length; i++)
+        {
+            FieldInfo field = typeof(T).GetField(headerNames[i]);
+            field.SetValue(gameData, Convert.ChangeType(values[i], field.FieldType));
+        }
+
+        return gameData;
     }
 
     /// <summary>
-    /// Load data about previous games from file (if any).
+    /// Convert GameData object to a csv string.
     /// </summary>
-    private void Load()
+    /// <param name="gameData">GameData to convert</param>
+    /// <param name="headerOnly">When true, returns a csv header string (names of fields),
+    /// otherwise returns a csv row string (values of fields)</param>
+    /// <returns>Csv string</returns>
+    private string GameDataToCsv(T gameData, bool headerOnly)
     {
-        if (File.Exists(dataPath))
+        StringBuilder csvString = new StringBuilder();
+        FieldInfo[] fields = GetFields(gameData);
+
+        for (int i = 0; i < fields.Length; i++)
         {
-            string json = File.ReadAllText(dataPath);
-            SaveData<T> loadedData = JsonUtility.FromJson<SaveData<T>>(json);
+            if (headerOnly)
+            {
+                csvString.Append(fields[i].Name);
+            }
+            else
+            {
+                csvString.Append(fields[i].GetValue(gameData));
+            }
+            if (i < fields.Length - 1)
+            {
+                csvString.Append(",");
+            }
+        }
+
+        return csvString.ToString();
+    }
+
+    /// <summary>
+    /// Return info on all public fields.
+    /// Order is: date, startTime, endTime, gameCompleted, then any
+    /// other fields in alphabetical order.
+    /// </summary>
+    private FieldInfo[] GetFields(T gameData)
+    {
+        Type type = gameData.GetType();
+        FieldInfo[] fields = type.GetFields();
+        FieldInfo[] sortedFields = new FieldInfo[fields.Length];
+
+        // We return date, startTime, endTime, gameCompleted first (as this is general data
+        // for all games, and useful to have at the start of the csv)
+        sortedFields[0] = type.GetField("date");
+        sortedFields[1] = type.GetField("startTime");
+        sortedFields[2] = type.GetField("endTime");
+        sortedFields[3] = type.GetField("gameCompleted");
+
+        // Then, all other fields sorted in alphabetical order
+        Array.Sort(fields, (x, y) => String.Compare(x.Name, y.Name));
 
-            if (loadedData.savedGames != null)
+        int nextIndex = 4;
+        foreach (FieldInfo field in fields)
+        {
+            if (!sortedFields.Contains(field))
             {
-                this.savedGames = loadedData.savedGames;
+                sortedFields[nextIndex] = field;
+                nextIndex++;
             }
         }
+
+        return sortedFields;
+    }
+
+    private void CheckSaveFileExists()
+    {
+        if (File.Exists(dataPath))
+        {
+            saveFileExists = true;
+        }
+        else
+        {
+            saveFileExists = false;
+        }
     }
 }
diff --git a/projects/AstroBalance/Assets/Scripts/SpaceWalking/SpaceWalkingManager.cs b/projects/AstroBalance/Assets/Scripts/SpaceWalking/SpaceWalkingManager.cs
index 712691ec..b34f5fbd 100644
--- a/projects/AstroBalance/Assets/Scripts/SpaceWalking/SpaceWalkingManager.cs
+++ b/projects/AstroBalance/Assets/Scripts/SpaceWalking/SpaceWalkingManager.cs
@@ -86,7 +86,9 @@ void Start()
     private void ChooseGameDifficulty()
     {
         SaveData<SpaceWalkingData> saveData = new(saveFilename);
-        IEnumerable<SpaceWalkingData> lastNGamesData = saveData.GetLastNGamesData(nGamesToUpgrade);
+        IEnumerable<SpaceWalkingData> lastNGamesData = saveData.GetLastNCompleteGamesData(
+            nGamesToUpgrade
+        );
 
         if (debugHeadTurns)
         {
diff --git a/projects/AstroBalance/Assets/Scripts/StarCollector/StarCollectorManager.cs b/projects/AstroBalance/Assets/Scripts/StarCollector/StarCollectorManager.cs
index e500ea63..89083f85 100644
--- a/projects/AstroBalance/Assets/Scripts/StarCollector/StarCollectorManager.cs
+++ b/projects/AstroBalance/Assets/Scripts/StarCollector/StarCollectorManager.cs
@@ -55,7 +55,7 @@ void Start()
 
         // Load last game data (if any) from file + choose time limit for this game
         SaveData<StarCollectorData> saveData = new(saveFilename);
-        StarCollectorData lastGameData = saveData.GetLastGameData();
+        StarCollectorData lastGameData = saveData.GetLastCompleteGameData();
 
         if (lastGameData == null)
         {
diff --git a/projects/AstroBalance/Assets/Scripts/StarMap/StarMapManager.cs b/projects/AstroBalance/Assets/Scripts/StarMap/StarMapManager.cs
index 64864364..9b5f7b29 100644
--- a/projects/AstroBalance/Assets/Scripts/StarMap/StarMapManager.cs
+++ b/projects/AstroBalance/Assets/Scripts/StarMap/StarMapManager.cs
@@ -76,7 +76,7 @@ void Start()
     private void ChooseConstellationSize()
     {
         SaveData<StarMapData> saveData = new(saveFilename);
-        IEnumerable<StarMapData> lastNGamesData = saveData.GetLastNGamesData(maxScoreGames);
+        IEnumerable<StarMapData> lastNGamesData = saveData.GetLastNCompleteGamesData(maxScoreGames);
         int smallConstellationMaxLength = smallConstellation.GetNumberOfStars();
 
         // We haven't played enough games, to get maxScoreGames in a row
diff --git a/projects/AstroBalance/Assets/Scripts/StarSeek/StarSeekManager.cs b/projects/AstroBalance/Assets/Scripts/StarSeek/StarSeekManager.cs
index 93b95a59..0f7fc49e 100644
--- a/projects/AstroBalance/Assets/Scripts/StarSeek/StarSeekManager.cs
+++ b/projects/AstroBalance/Assets/Scripts/StarSeek/StarSeekManager.cs
@@ -65,7 +65,9 @@ void Start()
     private void ChooseGameTimeLimit()
     {
         SaveData<StarSeekData> saveData = new(saveFilename);
-        IEnumerable<StarSeekData> lastNGamesData = saveData.GetLastNGamesData(nGamesToUpgrade);
+        IEnumerable<StarSeekData> lastNGamesData = saveData.GetLastNCompleteGamesData(
+            nGamesToUpgrade
+        );
 
         if (lastNGamesData.Count() < nGamesToUpgrade)
         {