Sanctum 2 is a hybrid first-person shooter and tower defense game where players alternate between building phases and combat phases. In building mode you place towers, walls, and traps to create kill zones around a core that must be protected from alien hordes. When the wave starts, you switch to FPS view and fight alongside your towers using class-specific weapons and abilities. The game mixes strategic maze design with precise shooting, especially on harder difficulties or when replaying maps for leaderboard ranks. Most players experience Sanctum 2 either solo through the campaign or in online co-op with up to three friends. The practical demands shift dramatically between quiet building phases and the dense combat of later waves. Enemy swarms, multiple active towers, and particle effects create sudden spikes in on-screen activity that stress the CPU far more than the GPU. Because the game runs on an aging Unreal Engine 3, these spikes often appear as stuttering or inconsistent frame pacing rather than outright low average frame rates. For the high FPS scenario, the focus is on eliminating that stutter and minimizing input lag so mouse aiming feels instantaneous. High frame rates help with precise shots against fast-moving targets and improve overall responsiveness when manually kiting enemies through your defenses. Common pain points include frame-time instability during massive waves and the fact that the engine's menus are capped at low refresh rates. Many players mistakenly assume the 2013 title needs only basic hardware and end up with a system that feels choppy at elevated frame rates; the key is choosing components that keep simulation and rendering workloads from fighting each other.