Horror-themed adventure games have come and gone, but none quite like Lucius. Inspired by movies like The Omen and The Exorcist, Lucius is a third-person adventure game that puts you in the shoes of a six-year-old boy growing up in a wealthy household who just happens to be possessed by the devil. And unlike your typical horror-themed adventure game, instead of escaping from a creepy mansion with your life and limbs intact, this time you’re the one doing the killing. Lots of it.

At the Game Developer’s Conference, I met with Claas Wolter, PR Manager for publisher Lace Mamba Global, to get a sneak peek at this unusual game. Our demo began as Lucius, a seemingly normal six-year-old boy, wakes up in his bedroom to find a message from his “father” (a.k.a. Satan). The player’s mission, I soon learned, is to systematically eliminate Lucius’s family and other members of the household by whatever gruesome means necessary. To do so, you must orchestrate fatal “accidents” so that no one suspects you.

How did young Lucius end up in this mess? He has his grandfather to thank. Years earlier, the patriarch agreed to sell his first grandchild’s soul to the devil. Now Satan is making good on the bargain by driving Lucius to kill off members of his household one by one. Initially the boy doesn’t know why he’s compelled to do what he is, but as the game progresses, he (and the player) will gain a better understanding of the family history and what’s at stake.

The premise is a bit easier to stomach when you consider that the victims aren’t exactly in line for sainthood themselves. For example, Lucius’s uncle is a porn photographer who’s having affairs with multiple members of the household staff. In fact, one of these liaisons—a kitchen maid—is Lucius’s first target. Killing her will involve finding a padlock, following her to a walk-in freezer, and… you can probably guess how she meets her maker. Once the deed is done, Lucius must hide the evidence so no one suspects him.

If this all sounds soulless, well, that’s because it is. In the gameplay slice I saw, Lucius didn’t appear to feel remorse for his actions; he’s entirely under the devil’s control. Wolter explained that as the game progresses, a moral struggle does develop to some degree, but as in a horror movie, much of Lucius’s wicked fun comes from witnessing the gory depths to which the possessed character will sink, to carry out his father’s commands.

Lucius takes place in a large Victorian-influenced mansion. Even in the early version I saw, the graphics were impressive. The 3D world has a very open feel, with secondary characters moving between rooms and a day/night cycle prompting dramatic lighting changes as time passes. The player can control the camera to look around the detailed environments and the house itself is huge, with numerous rooms to explore. (I counted at least a dozen during our brief demo, and Wolter said there are also hidden areas to discover.) A map will be available to streamline navigation. Keyboard controls were used in the demonstration, but gamepads may also be supported in the final game.

The storyline spans about 20 days, with Satan giving Lucius daily instructions to kill a particular member of the household. (As you might expect, he and Lucius communicate via a Ouija board.) Though some activities will be optional, progress is mostly linear, with gameplay that primarily involves orchestrating fatal accidents and framing other characters for the crimes. Early puzzles have an emphasis on finding, using, and combining items correctly, while later tasks will also require the boy’s developing supernatural powers, such as telekinesis and mind control.

Above all, Lucius needs to be sneaky, because NPCs (including the police officers who show up to investigate the murders) can catch him in the act. This requires cunning on the player’s part, but Wolter stressed that gameplay relies less on stealthy timing than on setting up a situation properly. In many cases, you’ll need to make sure you’re well hidden before carrying out an action. For example, at once point Lucius must swipe a pack of cigarettes off a table. If you try to take them while Lucius is in plain sight, he’ll get caught. Instead, you must grab them while hiding behind a nearby chair. Lucius saves automatically at certain checkpoints, so if you do get caught, the game resumes from the last save.

Precocious young Lucius takes notes in his diary, which can provide hints if you get stuck, and other characters sometimes drop clues if you talk to them. In another user-friendly feature, the game will have a hotspot finder to identify areas where you can interact. In my demo, this took the form of yellow outlines that appeared around interactive items as Lucius approached them, but the presentation may be different in the final version.

This debut game from Helsinki-based Shiver Games will release on PC this summer. To learn more about Lucius, read on for Jack Allin’s interview with Shiver Games’ co-founder Johannes Aikio.