Scarlett had a nice life up there in the mountains above Venice. Living in a small miner village called San Pasquale and being in love with a future hero, everything seemed possible. But in truth she never really fit in because she was an orphan of questionable heritage. When one day the village is attacked by assassins searching for her, this becomes more clear than ever. The village gets destroyed and her betrothed Benedict is killed. The next day, the survivors tell Scarlett to leave. Her goal is Venice, where the so-called Undead Five threaten the cosmic balance.

Venetica is an action role-playing game with the player looking over Scarlett's shoulder while traveling around the world. Several typical role-playing tasks await the player in the game, including different quests, conversations with NPCs through multiple-choice dialogues, fighting many enemies, collecting items and earning experience points to level up and learn new abilities. Quests and dialogues often require the player to make decisions that influence not only the overall story, but in part also how the world around Scarlett reacts to her.

Scarlett can deal with the enemies by performing powerful combo attacks with her weapons. She has access to four types of weapons and two skill-trees littered with active and passive talents, and can acquire new weapons and armor over the course of the game. Hammers and axes allow Scarlett to destroy closed doors. She can also wield the Moonblade, a legendary upgradable weapon which alone can destroy undead creatures. Killing someone with the Moonblade restores Scarlett's shadow energy.

The latter is needed for Scarlett's special gift: as the daughter of Death, she doesn't die that easily. If enough shadow energy is available, she will instead rise again after a few seconds with half her hitpoints restored. However, if Scarlett is low on that energy, her death is permanent. Shadow energy is also used to enter the Shadow World for a short period of time. Everything in the Shadow World frozen, allowing Scarlett to escape from her enemies or get behind their backs. By entering the Shadow World, the player can also find portals and doors to areas which are hidden and inaccessible in the normal world. The player can also learn the ability Shadow Path to walk in and out of the Shadow World at will.