System Shock 2

First-person RPG-shooter set aboard a derelict starship in 2114. You're a soldier who wakes mid-crisis: the crew's been warped into a hive-mind organism called The Many, and SHODAN—a rogue AI—wants humanity under her thumb. Exploration means scrounging for ammo, audio logs that piece together what happened, and locked terminals. Character progression lets you spec into hacking, psionic powers, or weapon proficiency. Enemies include mutated crew and security droids. Resources are tight; you'll backtrack through dimly lit corridors as threats escalate. The horror comes from isolation and the constant sense you're outgunned. If you want shooters that make you manage inventory and think before every firefight, this nails it.