Players explore the underwater installation from a third-person viewpoint, searching rooms for key items, documents, ammunition, medical supplies, and access routes. Environmental hazards and flooding can alter how areas are traversed, while oxygen management adds pressure to exploration.

The objective is to investigate the disaster, restore access to parts of the facility, and survive encounters with mutated creatures. Progress is structured around connected facility sections, locked doors, switches, item-based puzzles, and boss encounters. Weapons and supplies must be used carefully because resources are limited.

Conserve ammunition by avoiding unnecessary fights when the route is clear. Search rooms thoroughly for oxygen, healing items, ammunition, and key objects before moving on.

Watch the oxygen supply during flooded or hazardous sections, and save before major exploration or boss encounters. Learn enemy attack patterns rather than relying on continuous fire, since resource shortages become more severe later in the game.