If you have Steam, drag the folder dt_dungeon into your:
"C:\Program Files\Valve\Steam\SteamApps\user\half-life" folder

The game should now appear under thirdd Party Games section in Your steam 'Play Games' window



If you have WON (non Steam) drag the folder dt_dungeon into your:
"C:\Sierra\Half-Life\valve" folder

Im sure if you are using WON you already know how to play this custom game, as it has been out for 7 years. If you don't, go blow yourself.
