diff --git a/GENESYSLauncher/GENESYSLauncher/Program.cs b/GENESYSLauncher/GENESYSLauncher/Program.cs
index 23084ff..1c6bf8b 100644
--- a/GENESYSLauncher/GENESYSLauncher/Program.cs
+++ b/GENESYSLauncher/GENESYSLauncher/Program.cs
@@ -38,7 +38,14 @@ private static void Main(string[] args)
 				{
 					if (Launcher.CreateGame(Launcher.GameType.HL2S).ValidateGamePath())
 					{
-						Launcher.LaunchGame(Launcher.GameType.HL2S);
+                        if (!Launcher.IsSteamAppInstalled(243730) || !Launcher.IsSteamAppInstalled(243750) || !Launcher.IsSteamAppInstalled(220))
+                        {
+                            MessageBox.Show("You must own and install a copy of Half-Life 2 or the Source SDK 2013 Base Singleplayer or Multiplayer in order to run " + Launcher.CreateGame(Launcher.GameType.HL2S).Name, Text, MessageBoxButtons.OK, MessageBoxIcon.Error);
+                        }
+                        else
+                        {
+							Launcher.LaunchGame(Launcher.GameType.HL2S);
+						}
 					}
 					else
 					{
@@ -51,7 +58,14 @@ private static void Main(string[] args)
 				{
 					if (Launcher.CreateGame(Launcher.GameType.CyberDiver_v1_00).ValidateGamePath())
 					{
-						Launcher.LaunchGame(Launcher.GameType.CyberDiver_v1_00);
+						if (!Launcher.IsSteamAppInstalled(243730) || !Launcher.IsSteamAppInstalled(243750) || (!Launcher.IsSteamAppInstalled(220) && !Launcher.IsSteamAppInstalled(380) && !Launcher.IsSteamAppInstalled(420)))
+						{
+							MessageBox.Show("You must own and install a copy of Half-Life 2, Half-Life 2 Episode One, and Half-Life 2 Episode Two, or the Source SDK 2013 Base Singleplayer or Multiplayer in order to run " + Launcher.CreateGame(Launcher.GameType.CyberDiver_v1_00).Name, Text, MessageBoxButtons.OK, MessageBoxIcon.Error);
+						}
+						else
+						{
+							Launcher.LaunchGame(Launcher.GameType.CyberDiver_v1_00);
+						}
 					}
 					else
 					{
@@ -64,7 +78,14 @@ private static void Main(string[] args)
 				{
 					if (Launcher.CreateGame(Launcher.GameType.CyberDiver_v1_20j).ValidateGamePath())
 					{
-						Launcher.LaunchGame(Launcher.GameType.CyberDiver_v1_20j);
+						if (!Launcher.IsSteamAppInstalled(243730) || !Launcher.IsSteamAppInstalled(243750) || (!Launcher.IsSteamAppInstalled(220) && !Launcher.IsSteamAppInstalled(380) && !Launcher.IsSteamAppInstalled(420)))
+						{
+							MessageBox.Show("You must own and install a copy of Half-Life 2, Half-Life 2 Episode One, and Half-Life 2 Episode Two, or the Source SDK 2013 Base Singleplayer or Multiplayer in order to run " + Launcher.CreateGame(Launcher.GameType.CyberDiver_v1_20j).Name, Text, MessageBoxButtons.OK, MessageBoxIcon.Error);
+						}
+						else
+						{
+							Launcher.LaunchGame(Launcher.GameType.CyberDiver_v1_20j);
+						}
 					}
 					else
 					{
@@ -77,7 +98,14 @@ private static void Main(string[] args)
 				{
 					if (Launcher.CreateGame(Launcher.GameType.L4DS).ValidateGamePath())
 					{
-						Launcher.LaunchGame(Launcher.GameType.L4DS);
+						if (!Launcher.IsSteamAppInstalled(550))
+						{
+							MessageBox.Show("You must own and install a copy of Left 4 Dead 2 in order to run " + Launcher.CreateGame(Launcher.GameType.L4DS).Name, Text, MessageBoxButtons.OK, MessageBoxIcon.Error);
+						}
+						else
+						{
+							Launcher.LaunchGame(Launcher.GameType.L4DS);
+						}
 					}
 					else
 					{
diff --git a/GENESYSLauncher/GENESYSLauncher/changelog.txt b/GENESYSLauncher/GENESYSLauncher/changelog.txt
index 81144d4..42045db 100644
--- a/GENESYSLauncher/GENESYSLauncher/changelog.txt
+++ b/GENESYSLauncher/GENESYSLauncher/changelog.txt
@@ -1,3 +1,5 @@
+v2.0.1:
+- Fixed a security issue involving the command line arguments.
 v2.0:
 - Redid the settings system to use Visual Studio's setting system.
 - Rewrote the code behind the scenes for better efficency.