The Castle of Grief is the first map in the hub of the same name.
You begin in a small room located in the north end. Once outside the starting room you are on the front door, north entrance, to the castle. It should be noted that like Heresiarch's Seminary the castle is guarded by many monsters right from the start.
The castle is protected by a wall running between five guard towers located roughly in the northwest, west, south, east and northeast. There are two openings in the wall – one in the north end center and one in the southwest corner. On both sides of both entrances are lifts to the castle wall.
Inside the walls are will find four buildings:
- The tower – round building, located in the map's center: Upon claiming this gear, the mouths in the columns begin shooting darts.
- The clockhouse – U-shaped, located in southwest corner (entrance from south).
- The firefloor – L-shaped, located in southeast corner (entrance from north): Upon claiming this gear, the holes in the floor above erupt with fireballs.
- The pillar house – located west.
Between you and a castle is a moat that has a wooden bridge in the middle. To raise the stairs you need to go into water on both sides of the bridge and pull the switches, thereby raising the stairs so you can enter the castle. You are at the north entrance. On either side of the entrance there are lifts to castle wall, but they aren't working yet.
Your first mission is to activate the clock in the clockhouse. To do this you need four clock gears; the order in which you acquire them is not important.
- Look inside the pillar house – there you see the gear immediately. Taking the clock gear activates a trap as the pillars drop.
- In the middle of the tower building is platform where the clock gear is. Taking it makes the pillars shoot darts, but running through seems to work fine.
- Go outside the walls through the south entrance (located in the southwest corner). Now you must go around the walls on both sides of the castle and activate four moon buttons hidden in corners. When done return to the tower. In the north end a ledge has lowered with the clock gear.
- Inside the tower building there is a moon button on a ledge in the east wall. Pushing it activates the lifts to castle wall level. Go on the wall and go to each of the five guard towers. In each there is inside a demon face button. After all five are activated enter the firefloor building and take the gear.
With all four clock gears enter the clockhouse and open the shutters on the wall. Insert the four clock gears to their corresponding places. When all four have been placed the clock begins to work and you get a message that in the tower a ledge has lowered (revealing a Dark Servant artifact). Riding the ledge up leads to a teleport switch to Gibbet.
The Forsaken Outpost exit is located at the map's southeast corner.
Due to a mapping oversight, an early version (1.0.) of this level includes a major shortcut. It allows for many of the hub's puzzles to be disregarded and also lets one skip the Dungeons completely. To access the shortcut, the player must turn into a pig, by either being shot with a Porkalator projectile in the tower or by bouncing an own Porkalator bullet back from a shield of a Slaughtaur in order to get hit by the bullet.
While being in pig's form, the player can slip through a low opening at the eastern end of the moat in front of the castle. Behind the opening, there is a portal to Effluvium that transports him to a position in the level that lies fairly near to another portal to the Forsaken Outpost. By traveling through the latter portal, the player is about to solve the most crucial puzzle of the hub, the Axe key puzzle. Once the player walks over a certain line in the hall where he had teleported to, the Axe key gets released in Gibbet. After the triggering, he must return to Effluvium where he can continue to Gibbet. When he gets there, he only needs to go to pick up the Axe key and enter the Axe door for the boss fight and the next hub.
By using the intended way to pass the hub, the player would appear to Castle of Grief from Effluvium after having solved the majority of puzzles and fought the way through the Dungeons. In an updated version of Hexen, the shortcut was blocked.