The gameplay of "Undying" in general follows the precepts of the first-person shooter genre. The game simulates the main character Patrick Galloway's point of view for the player, who uses a variety of weapons to defeat enemies within the game while progressing through a series of levels. As with most FPSs, Galloway has a certain amount of health, represented by a cross symbol and corresponding number at the bottom center-left of the screen. Each time the player is hurt by an enemy the health number is continually reduced until it reaches zero, at which point Galloway dies - an event which is usually marked by a third-person cut scene, unique to each enemy type, showing his gruesome final moments. To prevent this, health can be replenished when low using health packs. Galloway's maximum health can also be increased when using the alternate mode of a certain weapon, but it drains quickly back to the standard amount of health.