Context: 5 engaging themes for a first person shooter video game: 1. **Abandoned Military Base**: A sprawling, post-apocalyptic military complex crawling with mutated soldiers and rogue robots, ideal for challenging firearm combat. 2. **Cyberpunk City**: A neon-lit, futuristic urban environment with towering skyscrapers and dense alleyways, featuring cybernetically enhanced enemies and hacking mechanics. 3. **Alien Spaceship**: A vast alien vessel stranded on Earth, with eerie corridors, zero-gravity sections, and extraterrestrial creatures to encounter. 4. **Zombie-Infested Town**: A desolate town overrun by hordes of aggressive zombies, featuring intense close-quarters combat and puzzle-solving to find safe passage. 5. **Underwater Research Facility**: A deep-sea laboratory flooded with water, filled with mutated aquatic creatures, and requiring stealth and underwater exploration skills to survive. Take one of the themes and write a one paragraph storyline for a new level of a first-person shooter video game that is challenging and engaging.