Styx Shards of Darkness follows the journey of a young thief named Styx as he tries to take revenge on those who killed his mother. Styx must navigate through various cities, including Paris and Rome, by infiltrating high-security facilities and stealing valuable items.
The gameplay revolves around stealth, platforming, and combat. Players control Styx as he sneaks past guards, climbs walls, and fights enemies using a variety of skills and gadgets. The game features a day-night cycle and weather system, which affects the behavior of NPCs and the difficulty of certain levels.