The simplest way is to open your project in VS, and double click on "Properties" in the Solution Explorer pane.
In the page that opens, Click "Settings" on the left hand side, and you will get a page that is blank except for a central message: Click the message.
In the "Name" column, put "lvl2", set "Type" to "bool", leave "Scope" as "User", and enter "False" in the "Value" column.
Save and close the page.
In your console app you can now write:
if (Properties.Settings.Default.lvl2)
{
Console.Writeline("Sorry but you didn't unlock level 2 yet");
}
else
{
Console.Writeline("You entered level 2...");
}
And you can save a new value:
Properties.Settings.Default.lvl2 = true;
Properties.Settings.Default.Save();
The settings file is in your app/Bin/Release or app/Bin/Debug folder, and is human readable XML.