diff --git a/AdventOfCode.lpr b/AdventOfCode.lpr
index 753b82f..483f69d 100644
--- a/AdventOfCode.lpr
+++ b/AdventOfCode.lpr
@@ -23,10 +23,11 @@ uses
   {$IFDEF UNIX}
   cthreads,
   {$ENDIF}
-  Classes, SysUtils, CustApp, USolver, UTrebuchet, UCubeConundrum, UGearRatios, UScratchcards, UGiveSeedFertilizer,
-  UWaitForIt, UCamelCards, UHauntedWasteland, UNumberTheory, UMirageMaintenance, UPipeMaze, UCosmicExpansion,
-  UHotSprings, UPointOfIncidence, UParabolicReflectorDish, ULensLibrary, UFloorWillBeLava, UClumsyCrucible,
-  ULavaductLagoon, UAplenty, UPulsePropagation;
+  Classes, SysUtils, CustApp, Generics.Collections, USolver,
+  UTrebuchet, UCubeConundrum, UGearRatios, UScratchcards, UGiveSeedFertilizer, UWaitForIt, UCamelCards,
+  UHauntedWasteland, UNumberTheory, UMirageMaintenance, UPipeMaze, UCosmicExpansion, UHotSprings, UPointOfIncidence,
+  UParabolicReflectorDish, ULensLibrary, UFloorWillBeLava, UClumsyCrucible, ULavaductLagoon, UAplenty,
+  UPulsePropagation;
 
 type
 
@@ -48,30 +49,51 @@ type
 procedure TAdventOfCode.RunPuzzleSolutions;
 var
   engine: TSolverEngine;
+  solvers: specialize TList<Integer>;
+  p: string;
+  n: Integer;
 begin
   WriteLn('### Advent of Code 2023 ###');
   engine := TSolverEngine.Create('data');
-  engine.RunAndFree(TTrebuchet.Create);
-  engine.RunAndFree(TCubeConundrum.Create);
-  engine.RunAndFree(TGearRatios.Create);
-  engine.RunAndFree(TScratchcards.Create);
-  engine.RunAndFree(TGiveSeedFertilizer.Create);
-  engine.RunAndFree(TWaitForIt.Create);
-  engine.RunAndFree(TCamelCards.Create);
-  engine.RunAndFree(THauntedWasteland.Create);
-  engine.RunAndFree(TMirageMaintenance.Create);
-  engine.RunAndFree(TPipeMaze.Create);
-  engine.RunAndFree(TCosmicExpansion.Create);
-  engine.RunAndFree(THotSprings.Create);
-  engine.RunAndFree(TPointOfIncidence.Create);
-  engine.RunAndFree(TParabolicReflectorDish.Create);
-  engine.RunAndFree(TLensLibrary.Create);
-  engine.RunAndFree(TFloorWillBeLava.Create);
-  engine.RunAndFree(TClumsyCrucible.Create);
-  engine.RunAndFree(TLavaductLagoon.Create);
-  engine.RunAndFree(TAplenty.Create);
-  engine.RunAndFree(TPulsePropagation.Create);
+
+  solvers := specialize TList<Integer>.Create;
+  if HasOption('p', 'puzzle') then
+  begin
+    for p in GetOptionValues('p', 'puzzle') do
+      if TryStrToInt(p, n) then
+        solvers.Add(n);
+  end
+  else
+    for n := 1 to 25 do
+      solvers.Add(n);
+
+  for n in solvers do
+    case n of
+      1: engine.RunAndFree(TTrebuchet.Create);
+      2: engine.RunAndFree(TCubeConundrum.Create);
+      3: engine.RunAndFree(TGearRatios.Create);
+      4: engine.RunAndFree(TScratchcards.Create);
+      5: engine.RunAndFree(TGiveSeedFertilizer.Create);
+      6: engine.RunAndFree(TWaitForIt.Create);
+      7: engine.RunAndFree(TCamelCards.Create);
+      8: engine.RunAndFree(THauntedWasteland.Create);
+      9: engine.RunAndFree(TMirageMaintenance.Create);
+      10: engine.RunAndFree(TPipeMaze.Create);
+      11: engine.RunAndFree(TCosmicExpansion.Create);
+      12: engine.RunAndFree(THotSprings.Create);
+      13: engine.RunAndFree(TPointOfIncidence.Create);
+      14: engine.RunAndFree(TParabolicReflectorDish.Create);
+      15: engine.RunAndFree(TLensLibrary.Create);
+      16: engine.RunAndFree(TFloorWillBeLava.Create);
+      17: engine.RunAndFree(TClumsyCrucible.Create);
+      18: engine.RunAndFree(TLavaductLagoon.Create);
+      19: engine.RunAndFree(TAplenty.Create);
+      20: engine.RunAndFree(TPulsePropagation.Create);
+    end;
+
   engine.Free;
+  solvers.Free;
+  WriteLn;
 end;
 
 procedure TAdventOfCode.DoRun;
@@ -79,7 +101,7 @@ var
   ErrorMsg: String;
 begin
   // quick check parameters
-  ErrorMsg := CheckOptions('h', 'help');
+  ErrorMsg := CheckOptions('hp:', ['help', 'puzzle:']);
   if ErrorMsg <> '' then
   begin
     ShowException(Exception.Create(ErrorMsg));
@@ -95,7 +117,6 @@ begin
     Exit;
   end;
 
-  { add your program here }
   RunPuzzleSolutions;
 
   // stop program loop
@@ -115,8 +136,13 @@ end;
 
 procedure TAdventOfCode.WriteHelp;
 begin
-  { add your help code here }
-  writeln('Usage: ', ExeName, ' -h');
+  WriteLn('Usage: ', ExeName, ' [Options]');
+  WriteLn('Options:');
+  WriteLn('  --help, -h');
+  WriteLn('      Shows this usage help.');
+  WriteLn('  --puzzle=<n>, -p <n>');
+  WriteLn('      Instead of running all solvers, only run the one for day <n>.');
+  WriteLn('      Integer from 1 to 25. Can be specified multiple times.');
 end;
 
 var