GOG.com wants to help you complete your Gabriel Knight collection. This weekend, until Monday, May 24 at noon EDT, they’re offering a 30% discount if you buy all three parts of the series (Gabriel Knight: Sins of the Fathers, Gabriel Knight 2: The Beast Within and Gabriel Knight 3: Blood of the Sacred, Blood of the Damned) or if you complete your collection of GK games. Click here to grab these classic adventure games at a great discount.