Fiona, the player-character, must be guided through Belli Castle, its grounds and outbuildings until she can find a way to escape. Along the way, players must solve puzzles, unlock doors and evade, hide or attempt to fight back against the castle's inhabitants. Fiona is accompanied by Hewie, a white German Shepherd dog. The two must work as a team to solve certain puzzles and outwit their pursuers.[4]

During the game, the castle's inhabitants chase and attack Fiona, and if evaded long enough will cease for a set interval. While it is possible to retaliate with kicks, Hewie's bites, or alchemically created weapons, the game's focus is on the player evading enemies long enough to find a hiding spot. The castle's staff chase Fiona individually until defeated in a boss battle, after which a different enemy will pursue Fiona.[5] Two enemies exist in addition to the castle's keepers, neither are dangerous to Fiona but can alert Fiona's pursuers to her location and cause panic. The first are small floating orbs of blue light known as Luminescents, which follow Fiona and emit a loud noise if they come into contact with her. The other enemy type are small grotesque, fetus resembling homunculi, who attach themselves to Fiona's legs while letting out a piercing yell.

Hewie joins Fiona early in the game, following different player-issued commands to perform actions like barking or growling when he detects a trap or threat. He can be commanded to stay, follow, attack, fetch and to shake hands.[4] In order to maintain a good relationship with her new companion, Fiona must issue commands to Hewie, praising or scolding him depending on whether or not he obeys. Praising or healing him when he becomes injured also maintains his interest.[6] Hewie will ignore Fiona's commands and wander off if not given enough attention, and if he is repeatedly mistreated he may even attack her. On the normal difficulty setting, Hewie can be knocked unconscious from sustaining too many injuries but can be revived. On the hard difficulty setting, he is slain after receiving the same level of injuries, causing the game to end.

When faced with certain scripted events or prolonged enemy attacks and chases, Fiona becomes fearful. If allowed to remain fearful for too long she will enter panic mode and run. Panic mode causes blurriness of the screen, saturation of the surroundings and a freeze-frame effect, and the control pad vibrates in time with Fiona's heartbeat. The player is unable to stop Fiona running and must try to prevent her from running into walls and objects. Running into scenery causes her to collapse and crawl away; at this point further damage will kill her. Hewie can only be called for help during panic mode, encouraging him to attack any pursuer and prevent Fiona from being killed. If enemies are avoided long enough panic mode ends.

The player-character and protagonist of Haunting Ground is eighteen-year-old Fiona Belli, who before the start of the game was involved in a car accident that killed her parents.[7] Although Fiona is not very athletic, she makes up for this with her quick mind.[8] She rescues and befriends a white German Shepherd named Hewie.[9] Throughout her exploration of the castle, she encounters several characters: Debilitas, a large, mentally disabled man who works as the gardener for the castle; Daniella, a homunculus unable to taste, feel pain or pleasure who cooks and does the household work around the castle;[10] Riccardo, the castle's groundskeeper; and Lorenzo Aureolus Belli, who does everything in his power to help Fiona.

Fiona Belli awakes in a cage in the butcher's room of a castle. She has just been involved in a car accident with her parents, but her memories of this accident are vague. Noting that the cage that keeps her prisoner was left unlocked, she steps out but is startled by a large, fierce animal snarling and then running past her. She quickly begins searching for answers and a way out of the castle. Along the way, she befriends the animal that initially frightened her, who is a white German Shepherd named Hewie, and who turns out to be a valuable ally. As Fiona's predicament gets more and more disturbing, she learns that she is the carrier of the Azoth, which is what the castle's residents are after.