This could potentially be first person or third person I believe. I dont know what would work better.
You start out alone and lost in a cave with no equipment except for a headlamp.
Your goal is to navigate the cave system without falling to your death or drowning or running out of light before working your way to safety. Along your way you will need to explore or scavenge to pick up items lost by past cave divers. There could be pick ups such as repelling equipment, scuba gear, food, batteries and fire starters etc.
Inventory could have a minimap grows as you uncover more areas. A battery bar that shows how much light you have left.
Maybe more than one way out as you could potentially u