Castle Creep addon - Half-Life

Mission Briefing :
To : CLASSIFIED
Code Name : Gordon Freeman
File number : X327
Subject : Police raid on Castle Creep
Time of commencement of operation : 0100
Operation objective : Seizure of Castle Creep and arrest of all persons involved in illegal genetic manipulation and/or illegal use of arms
Agents mission objective : Neutralisation of Edward Marsden
Location : Castle Creep
Briefing :A year ago, a wealthy businessman by the name of Edward Marsden bought the ancestral home of the Von Creep family seemingly with the intention of renovating it for residential use. It has now come to light that this man has been using the castle for illegal operations and as a base for a crime syndicate from which he has made most of his wealth illegally. The castle has now become the base of Marsden's small private army of mercenary soldiers who are there to guard Marsden and to hide the true nature of the their operations. The castle has been under surveillance for the past six months but it was only a day ago that the police detectives in charge of the operation secured enough evidence to prompt a police raid on the castle.
Reports suggest that Marsden has been using the castle mainly for arms trafficking but it has been discovered that he has also been researching new forms of weapons mainly in the form of genetically engineered viruses and genetically altered animals. It is unknown to what extent these experiments have reached however, there have been some alarming rumours in the criminal underworld of human testing and creatures designed specifically for war.
At 0900 hours tomorrow morning a large squad of armed police will raid the castle to capture all persons involved in illegal operations. It is predicted that there will be some strong resistance from Marsden's soldiers and it is feared that Marsden himself may have an escape plan prepared and will slip away while his men keep the police away. You have been assigned to prevent Marsden from getting away by whatever means possible. A picture of Edward Marsden is provided below. You will be dropped just outside the castle at 0100 hours , 8 hours before the raid begins. We believe you will be able to get into the castle through an unguarded door. From then on you're by yourself. It is your mission to covertly make your way through the castle, to find Marsden and to capture or eliminate him.The castle will be well guarded and possibly booby-trapped. You are recommended not to engage the enemy unless you are attacked and it is advised that you remain undetected for as long as possible. Due to the tight security network surrounding the castle you will be carrying no weapons to avoid detection. Once inside you may have to find some weapons and perhaps a hazard suit.Upon completion of the mission you will be collected by a silent helicopter and flown out of the area after which the raid will begin. We are relying on you to prevent Marsden from escaping; he is a dangerous man who may set up a similar operation if he gets away.
Description and background of location : Castle Creep is a large medieval castle situated in an arid valley 8 miles west of CLASSIFIED. It is a large stone building roughly 2 acres in size. Most of it is currently in a state of disrepair as it has been uninhabited for some two centuries however some parts have been recently renovated by it's new owners. It was built in the 13th Century by the De Creep family and was their ancestral home for some 300 years before they died out in the 1700s. The old parts will consist of thin stone corridors and wooden stairs containing mainly rubble and other debris left over from two centuries ago. These areas are likely to be dark and possibly structurally unsound. Corridors and doorways may be blocked so it may be necessary to find other routes. The layout of the newer areas is unknown. It is predicted that these will contain various laboratories, sleeping quarters and the private rooms of Edward Marsden. Be on the alert in these areas as Marsden's men will be guarding them.
This is a classified document, the contents of which should not be discussed with anyone nor should it be reproduced in any form. It is recommended that you destroy it after reading its contents or conceal it in a suitable location.
By order of Sargent Bloggs - Chief of police