diff --git a/Makefile b/Makefile
index d87b396..48ce1e9 100644
--- a/Makefile
+++ b/Makefile
@@ -8,3 +8,6 @@ tests: ## run all tests
 
 test: ## name=[test name]: run a single test with logging
 	dotnet test MultiversalDiplomacyTests -l "console;verbosity=normal" --filter $(name)
+
+repl: ## execute the repl
+	dotnet run --project MultiversalDiplomacy repl
diff --git a/MultiversalDiplomacy/Script/ReplScriptHandler.cs b/MultiversalDiplomacy/Script/ReplScriptHandler.cs
index c8ed795..4827621 100644
--- a/MultiversalDiplomacy/Script/ReplScriptHandler.cs
+++ b/MultiversalDiplomacy/Script/ReplScriptHandler.cs
@@ -1,3 +1,5 @@
+using MultiversalDiplomacy.Model;
+
 namespace MultiversalDiplomacy.Script;
 
 /// <summary>
@@ -9,7 +11,53 @@ public class ReplScriptHandler : IScriptHandler
 
     public IScriptHandler? HandleInput(string input)
     {
-        Console.WriteLine($"[{input}]");
+        var args = input.Split(' ', StringSplitOptions.RemoveEmptyEntries);
+        if (args.Length == 0)
+        {
+            return this;
+        }
+
+        var command = args[0];
+        switch (command)
+        {
+            case "help":
+            case "?":
+                Console.WriteLine("Commands:");
+                Console.WriteLine("  help, ?: print this message");
+                Console.WriteLine("  map <variant>: start a new game of the given variant");
+                Console.WriteLine("  stab: stab");
+                break;
+
+            case "stab":
+                Console.WriteLine("stab");
+                break;
+
+            case "map" when args.Length == 1:
+                Console.WriteLine("Usage:");
+                Console.WriteLine("  map <variant>");
+                Console.WriteLine("Available variants:");
+                Console.WriteLine($"  {string.Join(", ", Enum.GetNames<MapType>().Select(s => s.ToLowerInvariant()))}");
+                break;
+
+            case "map" when args.Length > 1:
+                string mapType = args[1].Trim();
+                if (!Enum.TryParse(mapType, ignoreCase: true, out MapType map)) {
+                    Console.WriteLine($"Unknown variant {mapType}");
+                    Console.WriteLine("Available variants:");
+                    Console.WriteLine($"  {string.Join(", ", Enum.GetNames<MapType>().Select(s => s.ToLowerInvariant()))}");
+                    break;
+                }
+                World world = World.WithMap(Map.FromType(map));
+                Console.WriteLine($"Created a new {map} game");
+                return new SetupScriptHandler(world);
+
+            default:
+                // noop on comments that begin with #
+                if (!command.StartsWith('#')) {
+                    Console.WriteLine($"Unrecognized command: {command}");
+                }
+                break;
+        }
 
         return this;
     }
diff --git a/MultiversalDiplomacy/Script/SetupScriptHandler.cs b/MultiversalDiplomacy/Script/SetupScriptHandler.cs
new file mode 100644
index 0000000..45f5b0f
--- /dev/null
+++ b/MultiversalDiplomacy/Script/SetupScriptHandler.cs
@@ -0,0 +1,167 @@
+using System.Diagnostics.CodeAnalysis;
+
+using MultiversalDiplomacy.Model;
+
+namespace MultiversalDiplomacy.Script;
+
+/// <summary>
+/// A script handler for modifying a game before it begins.
+/// </summary>
+public class SetupScriptHandler(World world) : IScriptHandler
+{
+    public string Prompt => "5dp> ";
+
+    public World World { get; private set; } = world;
+
+    public IScriptHandler? HandleInput(string input)
+    {
+        var args = input.Split(' ', StringSplitOptions.RemoveEmptyEntries);
+        if (args.Length == 0)
+        {
+            return this;
+        }
+
+        var command = args[0];
+        switch (command)
+        {
+            case "help":
+            case "?":
+                Console.WriteLine("commands:");
+                Console.WriteLine("  begin: complete setup and start the game");
+                Console.WriteLine("  list <type>: list things in a game category");
+                Console.WriteLine("  option <name> <value>: set a game option");
+                Console.WriteLine("  unit <power> <type> <province> [location]: add a unit to the game");
+                Console.WriteLine("       <province> may be \"province/location\"");
+                break;
+
+            case "begin":
+                return null; // TODO
+
+            case "list" when args.Length == 1:
+                Console.WriteLine("usage:");
+                Console.WriteLine("  list powers: the powers in the game");
+                Console.WriteLine("  list units: units created so far");
+                break;
+
+            case "list" when args[1] == "powers":
+                Console.WriteLine("Powers:");
+                foreach (string powerName in World.Powers)
+                {
+                    Console.WriteLine($"  {powerName}");
+                }
+                break;
+
+            case "list" when args[1] == "units":
+                Console.WriteLine("Units:");
+                foreach (Unit unit in World.Units)
+                {
+                    Console.WriteLine($"  {unit}");
+                }
+                break;
+
+            case "option" when args.Length < 3:
+                throw new NotImplementedException();
+
+            case "unit" when args.Length < 4:
+                Console.WriteLine("usage: unit [power] [type] [province] <location>");
+                break;
+
+            case "unit":
+                string power = args[1];
+                string type = args[2];
+                string province = args[3];
+                string? location = args.Length >= 5 ? args[4] : null;
+                if (ParseUnit(power, type, province, location, out Unit? newUnit)) {
+                    World = World.Update(units: World.Units.Append(newUnit));
+                    Console.WriteLine($"Created {newUnit}");
+                }
+                break;
+
+            default:
+                // noop on comments that begin with #
+                if (!command.StartsWith('#')) {
+                    Console.WriteLine($"Unrecognized command: {command}");
+                }
+                break;
+        }
+
+        return this;
+    }
+
+    private bool ParseUnit(
+        string powerArg,
+        string typeArg,
+        string provinceArg,
+        string? locationArg,
+        [NotNullWhen(true)] out Unit? newUnit)
+    {
+        newUnit = null;
+
+        // Parse the power name by substring matching.
+        var matchingPowers = World.Powers.Where(p => p.StartsWithAnyCase(powerArg));
+        if (!matchingPowers.Any())
+        {
+            Console.WriteLine($"No power named \"{powerArg}\"");
+            return false;
+        }
+        if (matchingPowers.Count() > 1)
+        {
+            Console.WriteLine($"Ambiguous power \"{powerArg}\" between {string.Join(", ", matchingPowers)}");
+            return false;
+        }
+        string power = matchingPowers.First();
+
+        // Parse the unit type by substring matching.
+        var matchingTypes = Enum.GetNames<UnitType>().Where(t => t.StartsWithAnyCase(typeArg));
+        if (!matchingTypes.Any())
+        {
+            Console.WriteLine($"No unit type \"{typeArg}\"");
+            return false;
+        }
+        if (matchingTypes.Count() > 1)
+        {
+            Console.WriteLine($"Ambiguous unit type \"{typeArg}\" between {string.Join(", ", matchingTypes)}");
+            return false;
+        }
+        UnitType type = Enum.Parse<UnitType>(matchingTypes.First());
+
+        // Parse the province by matching the province name or one of its abbreviations,
+        // allowing location specifications separated by a forward slash, e.g. spa/nc.
+        if (provinceArg.Contains('/')) {
+            var split = provinceArg.Split('/', 2);
+            locationArg ??= split[1];
+            provinceArg = split[0];
+        }
+        var matchingProvs = World.Provinces.Where(pr
+            => pr.Abbreviations.Any(abv => abv.EqualsAnyCase(provinceArg))
+            || pr.Name.EqualsAnyCase(provinceArg));
+        if (!matchingProvs.Any())
+        {
+            Console.WriteLine($"No province matches \"{provinceArg}\"");
+            return false;
+        }
+        if (matchingProvs.Count() > 1)
+        {
+            Console.WriteLine($"Ambiguous province \"{provinceArg}\" between {string.Join(", ", matchingProvs)}");
+            return false;
+        }
+        Province province = matchingProvs.First();
+        Location location;
+        locationArg ??=  type == UnitType.Army ? "land" : "water";
+        var matchingLocs = locationArg is null
+            ? province.Locations.Where(loc
+                => type == UnitType.Army && loc.Type == LocationType.Land
+                || type == UnitType.Fleet && loc.Type == LocationType.Water)
+            : province.Locations.Where(loc
+                => loc.Name.EqualsAnyCase(locationArg)
+                || loc.Abbreviation.EqualsAnyCase(locationArg));
+        if (!matchingLocs.Any()) {
+            Console.WriteLine($"Province {province.Name} has no {locationArg} location");
+            return false;
+        }
+        location = matchingLocs.First();
+
+        newUnit = Unit.Build(location.Key, Season.First, powerArg, type);
+        return true;
+    }
+}